Design of retaining walls. Project documentation. Calculation of retaining walls Snip retaining walls

CENTRAL RESEARCH FACILITY

AND DESIGN AND EXPERIMENTAL INSTITUTE OF INDUSTRIAL BUILDINGS AND STRUCTURES (TsNIIPromzdanii) GOSSTROY OF THE USSR

REFERENCE MANUAL

to SNiP 2.09.03-85

Design of retaining walls

and basement walls

Developed for SNiP 2.09.03-85 “Construction of industrial enterprises”. Contains basic provisions for the calculation and design of retaining walls and basement walls of industrial enterprises made of monolithic and prefabricated concrete and reinforced concrete. Calculation examples are given.

For engineering and technical workers of design and construction organizations.

PREFACE

The manual is compiled for SNiP 2.09.03-85 “Structures of industrial enterprises” and contains the basic provisions for the calculation and design of retaining walls and basement walls of industrial enterprises made of monolithic, precast concrete and reinforced concrete with calculation examples and the necessary tabular values ​​of coefficients that facilitate the calculation.

In the process of preparing the Manual, certain calculation prerequisites of SNiP 2.09.03-85 were clarified, including taking into account soil adhesion forces, determining the inclination of the sliding plane of the collapse prism, which are supposed to be reflected in the addition to the specified SNiP.

The manual was developed by the Central Research Institute of Industrial Buildings of the USSR State Construction Committee (candidates of technical sciences A. M. Tugolukov, B. G. Kormer, engineers I. D. Zaleschansky, Yu. V. Frolov, S. V. Tretyakova, O. J. Kuzina) with the participation of NIIOSP them. N. M. Gersevanova of the USSR State Construction Committee (Doctor of Technical Sciences E. A. Sorochan, Candidates of Technical Sciences A. V. Vronsky, A. S. Snarsky), Foundation of the Project (engineers V. K. Demidov, M. L. Morgulis, I.S. Rabinovich), Kiev Promstroyproekt (engineers V.A. Kozlov, A.N. Sytnik, N.I. Solovyova).

1. GENERAL INSTRUCTIONS

1.1. This Manual has been compiled for SNiP 2.09.03-85 “Structures of industrial enterprises” and applies to the design of:

retaining walls erected on a natural foundation and located in the territories of industrial enterprises, cities, towns, access and on-site railways and roads;

basements for industrial purposes, both free-standing and built-in.

1.2. The manual does not apply to the design of retaining walls of main roads, hydraulic structures, special-purpose retaining walls (anti-landslide, anti-landslide, etc.), as well as to the design of retaining walls intended for construction in special conditions (on permafrost, swelling, subsidence soils, on undermined territories, etc.).

1.3. The design of retaining walls and basement walls should be based on:

master plan drawings (horizontal and vertical layout);

report on engineering and geological surveys;

technological specification containing data on loads and, if necessary, special requirements for the designed structure, for example, requirements for limiting deformations, etc.

1.4. The design of retaining walls and basements should be established on the basis of a comparison of options, based on the technical and economic feasibility of their use in specific construction conditions, taking into account the maximum reduction in material consumption, labor intensity and construction costs, as well as taking into account the operating conditions of the structures.

1.5. Retaining walls constructed in populated areas should be designed taking into account the architectural features of these areas.

1.6. When designing retaining walls and basements, design schemes must be adopted that provide the necessary strength, stability and spatial invariability of the structure as a whole, as well as its individual elements at all stages of construction and operation.

1.7. Elements of prefabricated structures must meet the conditions for their industrial production at specialized enterprises.

It is advisable to enlarge the elements of prefabricated structures, as far as the load-carrying capacity of the mounting mechanisms, as well as the manufacturing and transportation conditions allow.

1.8. For monolithic reinforced concrete structures standardized formwork and overall dimensions should be provided, allowing the use of standard reinforcement products and inventory formwork.

1.9. In prefabricated structures of retaining walls and basements, the design of units and connections of elements must ensure reliable transmission of forces, the strength of the elements themselves in the joint area, as well as the connection of additionally laid concrete at the joint with the concrete of the structure.

1.10. The design of structures for retaining walls and basements in the presence of an aggressive environment should be carried out taking into account additional requirements SNiP 3.04.03-85 “Protection of building structures and structures from corrosion”.

1.11. The design of measures to protect reinforced concrete structures from electrocorrosion must be carried out taking into account the requirements of the relevant regulatory documents.

1.12. When designing retaining walls and basements, one should, as a rule, use unified standard structures.

The design of individual structures of retaining walls and basements is allowed in cases where the values ​​of the parameters and loads for their design do not correspond to the values ​​​​accepted for standard structures, or when the use of standard structures is impossible based on local construction conditions.

1.13. This Manual considers retaining walls and basement walls backfilled with homogeneous soil.

2. MATERIALS OF CONSTRUCTION

2.1. Depending on the design solution adopted, retaining walls can be built from reinforced concrete, concrete, rubble concrete and masonry.

2.2. The choice of structural material is determined by technical and economic considerations, durability requirements, work conditions, the availability of local building materials and mechanization equipment.

2.3. For concrete and reinforced concrete structures, it is recommended to use concrete with a compressive strength of at least class B 15.

2.4. For structures subject to alternating freezing and thawing, the design must specify the grade of concrete for frost resistance and water resistance. The design grade of concrete is set depending on temperature regime, arising during the operation of the structure, and the values ​​of the calculated winter temperatures of the outside air in the construction area and are accepted in accordance with Table. 1.

Table 1

Conditions	Calculated	Concrete grade, not lower
designs	temperature	by frost resistance			by water resistance
freezing at	air, ° C	Structure class
alternating freezing and thawing
In water-saturated	Below -40	F 300	F 200	F 150	W 6	W 4	W 2
condition (for example, structures located in a seasonally thawing layer	Below -20 up to -40	F 200	F 150	F 100	W 4	W 2	Not standardized
soil in permafrost areas)	Below -5 to -20 inclusive	F 150	F 100	F 75	W 2	Not standardized
	5 and above	F 100	F 75	F 50	Not standardized
In conditions of occasional water saturation (for example, above-ground structures that are constantly exposed to	Below -40	F 200	F 150	F 400	W 4	W 2	Not standardized
weather conditions)	Below -20 to -40 inclusive	F 100	F 75	F 50		W 2 Not standardized
	Below -5 to -20	F 75	F 50	F 35*	Not standardized
	inclusive 5 and above	F 50	F 35*	F 25*	Same
Under air-humidity conditions in the absence of episodic water saturation, for example,	Below -40	F 150	F 100	F 75	W 4	W 2	Not standardized
structures, permanently (exposed to ambient air, but protected from atmospheric precipitation)	Below -20 to -40 inclusive	F 75	F 50	F 35*	Not standardized
	Below -5 to -20 inclusive	F 50	F 35*	F 25*	Same
	5 and above	F 35*	F 25*	F 15**

______________

* For heavy and fine-grained concrete, frost resistance grades are not standardized;

** For heavy, fine-grained and lightweight concrete, frost resistance grades are not standardized.

Note. The estimated winter outside air temperature is taken as the average air temperature of the coldest five-day period in the construction area.

2.5. Prestressed reinforced concrete structures should be designed primarily from class B 20 concrete; At 25; B 30 and B 35. For concrete preparation, class B 3.5 and B5 concrete should be used.

2.6. The requirements for rubble concrete in terms of strength and frost resistance are the same as for concrete and reinforced concrete structures.

2.7. For reinforcement of reinforced concrete structures made without prestressing, hot-rolled reinforcing steel bars of periodic profile should be used class A-I II and A-II. For installation (distribution) fittings, it is allowed to use hot-rolled reinforcement of class A-I or ordinary smooth reinforcing wire of class B-I.

When the design winter temperature is below minus 30°C, class A-II reinforcing steel of grade VSt5ps2 is not allowed for use.

2.8. As prestressing reinforcement for prestressed reinforced concrete elements, thermally strengthened reinforcement of class At-VI and At-V should generally be used.

It is also allowed to use hot rolled rebar class A-V, A-VI and thermally strengthened reinforcement of class At-IV.

When the design winter temperature is below minus 30°C, reinforcing steel of class A-IV grade 80C is not used.

2.9. Anchor rods and embedded elements must be made from rolled strip steel class C-38/23 (GOST 380-88) grade VSt3kp2 at design winter temperatures up to minus 30°C inclusive and grade VSt3psb at design temperatures from minus 30°C to minus 40° WITH. For anchor rods, steel S-52/40 grade 10G2S1 is also recommended at design winter temperatures up to minus 40°C inclusive. The thickness of the strip steel must be at least 6 mm.

It is also possible to use class A-III reinforcing steel for anchor rods.

2.10. In precast concrete and concrete elements structures, mounting (lifting) loops must be made of class A-I reinforcing steel grades VSt3sp2 and VSt3ps2 or class As-II steel grade 10GT.

When the estimated winter temperature is below minus 40°C, the use of VSt3ps2 steel for hinges is not allowed.

3. TYPES OF RETAINING WALLS

3.1. By constructive solution Retaining walls are divided into massive and thin-walled.

In massive retaining walls, their resistance to shear and overturning under the influence of horizontal soil pressure is ensured mainly by the wall’s own weight.

In thin-walled retaining walls, their stability is ensured by the wall’s own weight and the weight of the soil involved in the work of the wall structure.

As a rule, massive retaining walls are more material-intensive and more labor-intensive to construct than thin-walled ones, and can be used with an appropriate feasibility study (for example, when they are built from local materials, the absence of precast concrete, etc.).

3.2. Massive retaining walls differ from each other in the shape of the transverse profile and material (concrete, rubble concrete, etc.) (Fig. 1).

1 - universal wall panel (UPS); 2 - monolithic part of the sole

3.3. In industrial and civil construction, as a rule, thin-walled corner-type retaining walls shown in Fig. are used. 2.

Note. Other types of retaining walls (cellular, sheet piling, shell, etc.) are not considered in this Manual.

3.4. According to the manufacturing method, thin-walled retaining walls can be monolithic, prefabricated or precast-monolithic.

3.5. Thin-walled cantilever walls of the corner type consist of front and foundation slabs, rigidly interconnected.

In fully prefabricated structures, the front and foundation slabs are made from prefabricated elements. In prefabricated monolithic structures, the front slab is prefabricated, and the foundation slab is monolithic.

In monolithic retaining walls, the rigidity of the junction of the front and foundation slabs is ensured by the appropriate arrangement of the reinforcement, and the rigidity of the connection in prefabricated retaining walls is ensured by the device of a slotted groove (Fig. 3, A) or loop joint (Fig. 3, 6 ).

3.6. Thin-walled retaining walls with anchor rods consist of face and foundation slabs connected by anchor rods (ties), which create additional supports in the slabs that facilitate their work.

The interface between the front and foundation slabs can be hinged or rigid.

3.7. Buttress retaining walls consist of a capping slab, a buttress and a foundation slab. In this case, the soil load from the front slab is partially or completely transferred to the buttress.

3.8. When designing retaining walls from unified wall panels (UPP), part of the foundation slab is made of monolithic concrete using a welded connection for the upper reinforcement and an overlap joint for the lower reinforcement (Fig. 4).

4. BASEMENT LAYOUT

4.1. Basements should, as a rule, be designed as one-story. According to technological requirements, it is permissible to construct basements with a technical floor for cable distribution.

If necessary, it is allowed to construct basements with a large number of cable floors.

4.2. In single-span basements, the nominal span size should, as a rule, be 6 m; a span of 7.5 m is allowed if this is due to technological requirements.

Multi-span basements should be designed, as a rule, with a column grid of 6x6 and 6x9 m.

The height of the basement from the floor to the bottom of the ribs of the floor slabs must be a multiple of 0.6 m, but not less than 3 m.

The height of the technical floor for cable distribution in basements should be at least 2.4 m.

The height of passages in basements (when clean) should be at least 2 m.

4.3. There are two types of basements: free-standing and combined with a structure

During the construction of various types of buildings in areas with complex terrain (beams, ravines, etc.), the need for a retaining structure often arises. Such a strengthening structure has one main task - to prevent the collapse of soil masses. The article will discuss the construction of retaining walls.

• Decorative- effectively hide small differences in ground in the surrounding area. If the levels do not differ much and, accordingly, the height of the wall is low (up to half a meter), then it is installed with a slight depth of up to 30 cm.
• Fortifying perform the main function of restraining soil masses from sliding. Such structures are erected when the slope of the hill exceeds 8°. With their help, horizontal platforms are organized, thereby expanding the usable space.

Retaining wall photo

Design of retaining walls

Regardless of its purpose, a retaining wall has 4 elements:

• foundation;
• body;
• drainage system;
• drainage system.

The underground part of the wall, drainage and drainage serve to implement technical standards, and the body serves aesthetic purposes. In height they can be low (up to 1 meter), medium (no higher than 2 meters) and high (over 2 meters).

The rear wall of the structure can have the following slope:

• steep (with direct or reverse slope);
• flat;
• recumbent.

The profiles of the fortification walls are varied, mainly rectangular and trapezoidal. The latter structures, in turn, may have different slopes of the edges.

Effective loads on retaining walls

When choosing a material, and, accordingly, a foundation for raising walls, they are guided by the determination of the loads that act on the structure.

Vertical forces:

• own weight;
• top load, that is, weight pressing on the top of the structure;
• the backfill force acting on both the wall itself and part of the foundation.

Horizontal forces:

• soil pressure directly behind the wall;
• frictional force at the points of adhesion between the foundation and the soil.

In addition to the main forces, there are also periodic loads, these include:

• wind force, this is especially true when the structure is over 2 m high;
• seismic loads (in seismic hazard zones);
• vibration forces act in places where a road or railway line passes;
• water flows, particularly in lowlands;
• swelling of the soil in winter period and so on.

Stability of retaining walls

The construction of low retaining walls is carried out largely for decorative purposes; they do not require careful calculation of stability. An increase in this property is indicative of retaining engineering structures.

You can prevent walls from moving or overturning by applying the following measures:

• significantly reduces soil pressure on the rear edge; a small slope designed towards a hill;
• The side facing the ground is made rough. Protrusions are made in stone, brick, and block masonry, and chipping is done in monolithic retaining walls;
• a properly organized drainage system prevents erosion of the structure;
• the presence of a console in the front part of the wall provides additional stability, as it distributes part of the soil load;
• lateral (vertical) pressure is reduced by filling hollow materials (expanded clay) between the rear wall and the existing soil;
• For solid walls made of heavy materials, a foundation is required. For clay soil it is advisable to use a base belt type, weak soil (sandy, especially quicksand) - pile foundation.

Construction of a retaining wall

As for the material, its choice is based on many criteria, such as the height of the structure, water resistance, resistance to aggressive environments, durability, availability of building materials and the possibility of mechanizing the installation process.

Brick retaining wall

• When calculating brick retaining walls, a reinforced foundation is provided. Decorative qualities can be enhanced by using bricks that differ in size or color from the elements of the main masonry. Low wall(up to 1 meter) laid out independently. In cases where increased load is implied, you should resort to the services of professionals.

• For the work, ordinary red burnt brick or clinker with a high strength and moisture resistance coefficient is used. As a rule, for the construction of retaining walls it is required strip foundation.
• The width of the ditch for the base is equal to triple the width of the wall, that is, if construction is planned with one brick (25 cm), then this parameter will be equal to 75 cm. The depth should be at least 1 m. But the bottom is filled with a 20-30 cm layer of gravel or crushed stone , then a layer (10-15 cm) of sand, each backfill of material is compacted.
• The formwork is knocked down, its upper part should be 15-20 cm below ground level. For reinforcement, reinforcement bars are used, which are laid on broken brick or rubble stone. In any case, they should not just lie on a sand and gravel bed. Next, concrete grade 150 or 200 is poured.
• The clinker is placed in a dressing on the solution. The second row provides for the laying of drainage pipes Ø50 mm. When installing, ensure that the pipes are inclined towards the front of the edge; the recommended distance between them is 1 meter. It is important to monitor the movement of the seams. To prevent this from happening, you can use half bricks.
• It is worth noting that masonry with one brick is possible for the construction of walls up to 60 cm; for higher structures it is recommended to build with one and a half, two bricks, with the expansion of the lower part of the wall. Thus, a structure resembling a console is obtained.

Stone retaining wall

• Natural stone, like its artificial counterpart, is distinguished by high aesthetic properties. Besides appearance The finished wall allows you to harmoniously fit into the surrounding landscape, creating a single ensemble with nature.

• Here, both dry and wet methods of laying the material can be used. The first option is more labor-intensive and requires some skill, since it is necessary to adjust the stone to size, ensuring optimal fit to each other.
• The base for a stone retaining wall is made in the same way as for brick. A strip foundation is carried out followed by laying stone. If the construction of the wall is carried out without the use of mortar, then the seams are filled with planting material or garden soil. Later, plants with fibrous root systems are planted between the stones. As they develop, they will significantly strengthen the structural elements.

• In this case, you can organize the drainage system using a simplified method - leave 5 cm gaps between every 4th and 5th stone in the first row.
• Stone walls are recommended for the construction of structures no higher than 1.5 m.

Concrete retaining walls

• Such a monolithic structure is made using wooden formwork or bored piles.
• Factory reinforced concrete retaining wall
• Installation of a factory-made slab is carried out using lifting equipment. It can be cantilevered or buttressed. To install finished products, a foundation is not needed in dense soil. It is enough to dig a trench slightly wider than the size of the base of the slab or console.

Prefabricated retaining walls photo

• Gravel (crushed stone) and sand are laid at the bottom in layers of 15-20 cm. Thorough compaction is ensured by abundant watering. Reinforced concrete slabs are installed strictly vertically. They are connected to each other by welding reinforcement embedded elements. Next, a longitudinal drainage system is installed and the space is filled with soil.
• A reinforced concrete supporting wall on piles is recommended on weak (unstable) soils. The distance between the piles depends on the length of the slab; they can be located every 1.5, 2 or 3 meters. The diameter of the piles is usually from 300 to 500 mm.

DIY concrete retaining wall

• Greater stability of the wall is given by the console, made with a slope (10°-15°) towards the embankment. If we take a wall 2.5 meters high as an example, then the height of the underground part of the structure will be 0.8-0.9 m, and the width of the body will be 0.4 m.
• For the formwork, a trench is dug 1.2 m wide (here an allowance of 30 cm is provided on the front side and 50 cm for the rear edge) and 1.3 m deep (taking into account the organization of the sand and gravel cushion). The required slope is achieved by manually excavating the soil; this parameter is checked both when installing the formwork and when pouring it with concrete. If necessary, the tilt is adjusted.

• The base must be reinforced both longitudinally and vertically. The height of the rods protruding from the concrete should be at least half a meter. Allow the sole to gain strength; for concrete this period is about a month. It is not recommended to carry out any work on the sole before this time.
• For the convenience of constructing formwork for the body of the wall, moisture-resistant plywood of standard size 2440x1220x150 mm is taken. For one workpiece you will need 3 sheets, 2 of which will be used for full edges, and one plywood should be cut to the appropriate width for 2 sides.

• In subsequent work, one side wall is not used, since it serves as the wall of the previous part of the structure. Seam divergence between elements can be prevented through reinforcement. In this case, after pouring the material, holes are drilled in the side part and metal rods are inserted. They can be placed in a checkerboard pattern 40-50 cm apart from each other with a 30-40 cm exit from the wall body.
• Metal corners are used to connect the edges of the frame, since the weight of the concrete intended for pouring is high. Additional reinforcement will be 50x50 mm bars, which are nailed along the perimeter of the formwork. For reliability, spacers should be placed on three sides.
• If desired, the concrete surface can be decorated with natural or artificial stone.

• Blocks made of foam concrete, expanded clay concrete, gas or cinder blocks greatly facilitate the work and reduce construction costs. But the strength characteristics of such a wall will be an order of magnitude lower. In addition, masonry made from such material does not have an attractive appearance.

Wooden retaining wall

From the point of view of landscape design, wood is optimally suited for these purposes, but long service life is not its strongest point. To increase resistance to aggressive environments, considerable effort will have to be made through repeated treatment with impregnating agents.

In the design of a retaining wall, logs can be positioned either horizontally or vertically. Big difference regarding strength characteristics there is no. This material is used for the construction of walls not exceeding 1.5 m in height. To prevent rotting of the buried part of the log, it is necessary to burn it or treat it with liquid bitumen.

Vertical arrangement of logs in a retaining wall

• The length of the logs can be different, it all depends on the height difference. For stability, they are buried to a depth equal to 1/3 of the total length of the beam, so if this parameter is 2 m, then the dug part will be 60-70 cm.
• Installation of calibrated wood is carried out in a pre-dug trench. A 15 cm layer of crushed stone is poured into the bottom and compacted. The logs are placed as a solid wall, close to each other, strictly observing the vertical. Fastening is done using wire or nails driven in at an angle.

• Maximum stability of a log wall is achieved by filling the trench with a sand-cement mixture. The back side of a kind of tine is covered with a sealing material (roofing felt, roofing felt, etc.), after which it is backfilled with soil.

Horizontal arrangement of logs in a retaining wall

• Support pillars are dug in every 1.5-2 or 3 m; the more often they are located, the stronger the retaining wall will be. The wood used is necessarily treated with antiseptic agents.

Horizontal fastening can be done in several ways:

• Longitudinal grooves are pre-cut on the pillars on two opposite sides into which horizontal elements will be tightly inserted. In this case, the diameter of the supporting logs must be larger than the beams intended for transverse position;
• the second option involves fastening logs from the back side of the posts. In this case, the first beam is laid on the ground, so it is recommended to lay waterproofing material. The connection of horizontal logs to the supports is done with wire and/or nails.

Gabion retaining wall

• To install mesh structures, it is enough to level the surface and have coarse crushed stone (up to 150 mm) or small river boulders available to fill the sections. The main advantages of gabions are their flexibility and water permeability, which allows you to do without installing a drainage system.
• These wire boxes are simply assembled, then placed on level ground and covered with river or quarry stones. The following blocks are mounted using the same method. The sections are fastened together with wire with an anti-corrosion coating. This is a convenient method when you need to create many corner retaining walls.

• If you fill soil between the stones and sow plant seeds, then in a few years the wall will acquire an attractive appearance and blend organically into the surrounding landscape.

Retaining wall calculation

Before making a retaining wall, it is important to carefully consider all the nuances. Otherwise, illiterate calculations and negligent attitude to construction standards can lead to collapse.

Such walls no more than 1.5 meters high can be erected on their own. For the size of the sole, a coefficient of 0.5-0.7 multiplied by the height of the wall is taken. You can calculate the ratio of wall thickness to its height based on the type of soil:

• dense soil (limestone, quartz, spar, etc.) - 1:4;
• medium-density soil (shale, sandstone) - 1:3;
• soft soil (sand-clay particles) - 1:2.

If the height of the wall is large and construction is planned for weak soils, then you should turn to the services of specialized organizations. Calculations will be made in accordance with the requirements of SNiP.

In this case, many factors will be taken into account and the following calculations will be made based on the limit state of the retaining walls:

• stability of the position of the wall itself;
• soil strength, its possible deformation;
• the strength of the wall structure and the crack resistance of its elements.

Calculations for passive, active and seismic soil pressure will also be performed; clutch accounting; pressure groundwater and so on. The calculation is carried out taking into account maximum loads and covers the operational, construction and repair periods of the wall.

Of course, you can also use online calculators specially designed for these purposes. But you need to know that such calculations will be advisory in nature. Absolute accuracy of calculations is not guaranteed.

Drainage system for retaining wall

The organization of drainage and drainage requires special attention. The system ensures the collection and drainage of groundwater, melt and storm water, thereby preventing flooding and erosion of the structure. It can be longitudinal, transverse or combined.

• Transverse drainage requires Ø100 mm holes for every meter of wall.

• The longitudinal option involves placing a pipe located on the foundation along the entire length of the wall. Corrugated pipes are used for these purposes; due to their flexibility, they can be installed in difficult terrain. On straight sections use ceramic or asbestos cement pipes having holes at the top.

Retaining walls serve important purposes. Their construction should be entrusted to specialists or at least consulted with them on this issue. The slightest error in calculations can have very dire consequences.

1. Retaining wall: features of its structure
2. Popular building materials for constructing retaining walls
3. Design of retaining walls and basement walls: ways to increase their strength

The site for building a garage is not always perfectly level. If the construction site is located on an inclined surface (angle of inclination more than 80), then for the safety of the erected structure, care should be taken to additionally “preserve” the moving soil. For this purpose, retaining walls are used to prevent collapses and landslides of the earth on the slope. They play the role of reliable “shields” that balance the balance of forces in places where the terrain of the site varies. Supports are installed along the entire earthen “step”, completely edging its depressions and protrusions.

With the advent of new building materials, the design of retaining walls has changed significantly. Now, with the help of protective “bastions”, a site with a difficult “character” can not only be strengthened, but also decorated. It’s not for nothing that a decorative retaining wall is one of the popular techniques in landscape design, allowing you to effectively delimit zones of the site and place a certain emphasis on one of them.

The designs of retaining walls are different from each other, since they are designed for different degrees of influence of “hostile” forces trying to throw the support. But their “backbone” is unchanged and consists of the following basic “spare parts”:

• Ground part: BODY

The inner side of the wall is in contact with the ground, encircling the hill on the site. The front part of the “shield” is open, its shape can be flat or oblique (sloping towards a hill, cliff, ravine).

• Underground part: FOUNDATION

It compensates for the considerable soil pressure on the retaining wall. A massive drainage cushion of 20-30 cm (sand + crushed stone) must be placed under the base.

• Protective engineering Communication: WATER DISCHARGE and DRAINAGE

When designing retaining walls, protective measures must be taken to remove excess moisture and water, which inevitably accumulates behind their inner surface.

The construction of retaining walls is possible under certain favorable conditions. The main factors that a DIYer should take into account when deciding whether or not to organize this type of strengthening on his site are: the level of groundwater and soil freezing.

Here are the favorable parameters for successful construction:

The underground part of the retaining wall structure directly depends on the type of soil: the softer and more unstable it is, the deeper you should “dive” into it. Here is an example of calculating the depth of the foundation of a retaining wall for independent design:

• If the site has dense clay soil, then the depth of the foundation is 1/4 of the height of the retaining wall
• If the soil on the site is of medium looseness, then the depth of the foundation is 1/3 of the height of the retaining wall
• If the site has soft, loose soil, then the depth of the foundation is 1/2 the height of the retaining wall

As for the ground part of retaining walls, then for them independent device there is a certain limitation: the height of the “support” should not exceed 1.4 m. For the construction of a taller shield, specialized specialists should be involved, since strong soil pressure on the retaining wall requires more complex calculations when designing it. Now on the Internet there is a huge selection of software products that calculate all the necessary parameters of this auxiliary structure. But there is one “but”. They are also designed for “shields” up to 1.4 m high, since more massive structures require a special approach that does not fall under the standard calculation algorithm.

Another important parameter that is necessary for the stability of the protective “shield” is the thickness of the body of the massive retaining wall. It directly depends on the height of the structure and the type of soil: the higher the support and the softer the soil, the wider the supporting “leg” should be. And vice versa.

For DIYers, an example of calculations for a retaining wall of this type for “all occasions” will be useful:

• If the soil on the site is loose: the thickness of a massive retaining wall = 1/2 of its height
• If the soil is in an area of ​​medium density: the thickness of a massive retaining wall = 1/3 of its height
• If the soil on the site is dense and clayey: the thickness of the massive retaining wall = 1/4 of its height

Designing and calculating the parameters of thin retaining walls requires experience, since numerous examples of homemade overturned “shields” indicate that the likelihood of their fatal end is too high.

Popular building materials for constructing retaining walls

CONCRETE

This is the undisputed leader among building materials used for these purposes. You can pour concrete retaining walls yourself, buy completely ready-made modules, or build them from separate blocks. The strength and heaviness of the building material is the main reason for its widespread use for the construction of high protective structures. Concrete retaining walls are not distinguished by their aesthetic beauty and are rather monotonous, so they are trying to transform them with the help of decorative finishing coatings.

For a homemade product the most the best option is a monolithic “shield” design:

• The foundation and body of a concrete retaining wall is poured using removable formwork according to a standard “scenario” (for more details, see the section “Foundation for a garage”, “Walls for a garage”)

The easiest way is to use ready-made factory models of concrete retaining walls, which are installed in the required location using special equipment. But in this case, one should take into account the additional burden on the budget due to the delivery of blocks and rental of lifting equipment.

Reinforcement of concrete retaining walls

Reinforcement of retaining walls is carried out taking into account the “problem” areas of the structure. The most dangerous stress points: the top and the connection line between the foundation and the “shield” body. They require an increase in the density of the iron frame.

To calculate the reinforcement of retaining walls, special programs are used, where you can accurately select the thickness, pitch and brand of rods. But for clarity, we will indicate the basic principles correct reinforcement retaining walls that will help DIYers properly strengthen the monolithic structure of the protective structure.

The main force that the iron mesh inside the “shield” body must fight is bending. The calculation of retaining walls indicates that the main reinforcement of their body is located in a vertical plane, and the transverse bars (transverse reinforcement) are thinner (20% of the main section) strictly perpendicular to it. In the foundation, the transverse rods are laid strictly perpendicular to the main reinforcement of the ground part of the shield.

Here is an example of calculating a retaining wall:

If its thickness is more than 25 cm, the pitch of the main reinforcement is no more than 25 cm.
With a “shield” thickness of 15-25 cm, the pitch of the main reinforcement is no more than 15 cm.
Transverse reinforcement is installed in increments of no more than 25 cm.

As for the concrete grade, a B10-B15 solution is prepared for a monolithic retaining wall structure.

ROUND CONCRETE

In areas rich in rubble stone (flat cobblestones), this type of retaining wall masonry is practiced. You should choose consumable building materials meticulously, since for a high-quality “shield” the rubble must correspond in strength to the M150 grade. B7.5 concrete solution is used for pouring.

Rubble concrete masonry is advantageous in that for the construction of a homemade wall, a homemade wall does not bother with reinforcement. The stone copes well with the opposing forces that arise. All that remains is to study all the features of rubble concrete masonry, the main of which are:

• The ratio of solution and buta is 50 to 50
• The width of the stone should be equal to 1/3 of the width of the wall
• The stones must be clean and moistened for better adhesion to the solution
• The stone is not laid close to the edges of the wall (gap ≈3 cm)

The optimal width of rubble concrete masonry is 0.6 m (more is irrational). You can read more about the technology for performing the work in the section “Rubbed concrete foundation”.

STONE

This method is more labor-intensive, since the technology of stone masonry is complex due to the forced adjustment of working elements. Stone masonry retaining walls are a spectacular decoration of the site. Therefore, if any of the DIYers decide to take such a step, here are some working recommendations:

• The dressing of masonry seams for rows of stones should be at least 10 cm, and for corner elements - at least 15 cm
• For work, choose hard stones: basalt, quartzite, etc.
• If the masonry is carried out using mortar, then its grade should be at least M50
• When laying dry bricks, fill the gaps between the stones with soil.

The optimal width of a stone retaining wall is 0.6 m.

BRICK

This classic building material is often used for the construction of vertical retaining walls. Their thickness is 12 - 37 cm (half - one and a half bricks, respectively). The design of brick retaining walls is simplified by the presence of ready-made calculation tables, where for each wall height there is a complete breakdown of material consumption. The quantity is also indicated here. brick rows and a diagram of their laying, which is very convenient for a novice DIYer.
For example, for a retaining wall 60 cm high and ½ brick thick, you will need 8 rows of elements. For 1 sq. m of the erected “shield”, 62 bricks should be prepared.

TREE

A wooden support is the weakest “shield”, but it looks the most harmonious in the lap of nature. But if your area has a humid climate, then this decor is not suitable for your site, as it will last only one or two seasons.

For the construction of wooden retaining walls, logs of the same cross-section are used. They are dug in to the required calculated depth, having previously treated the tips with hot bitumen. Having laid vertical pillars in a dense row in the trench, connecting them together with nails or wire, the base of the “shield” is carefully cemented. This is the most simple circuit to make a wooden retaining wall. Horizontal laying of logs is more difficult to perform, where you need to cut grooves in the elements to correctly connect the working elements.

Design of retaining walls and basement walls: ways to increase their strength

There are a sufficient number of types of retaining walls, the difference between which lies in the structural features of the main structural elements. We are talking about the type of foundation (shallow, recessed), methods of finishing the front surface, and assembly features of the structure. Let us first dwell on the fundamental differences in the methods of strengthening “different-caliber” shields.

It is no coincidence that we included in this chapter not only the design features of retaining walls, but also basement walls. After all, they are similar in their key function: resisting the pressing force of the adjacent soil.

Design of retaining walls: features of massive and thin wall construction

Retaining walls can be massive or thin (the minimum thickness of a reinforced concrete support is 10 cm). The latter, due to the small thickness of the “shield”, cannot adequately withstand the pressure of the soil. The balancing of forces occurs due to the special design of the foundation slab, the elongated part of which is directed towards the soil embankment, which makes it work as a counterweight. The above-ground part of the “support” is rigidly fixed in the underground “leg”. This type of retaining wall arrangement has a special name – cantilever.

According to the method of fastening the above-ground and underground parts of the cantilever structure of the shield, they are distinguished:

• Corner cantilever retaining wall

Consists of two plates rigidly connected to each other. If the retaining wall is prefabricated, then the connection of the above-ground and underground parts of the structure is made using a recess in the foundation slab or using the loop method. For a monolithic support, the close “connection” of two mutually perpendicular slabs is achieved through their internal reinforcement.

• Anchor cantilever retaining wall

In this type of retaining wall design, the two slabs are connected using anchor ties, which contribute to their additional stability. The fastener can be made using a hinge or wedge method.

• Buttress cantilever retaining wall

This type of “shield” consists of a foundation, ground slab and buttress, which takes on a certain share of the soil pressure on the retaining wall.

Massive retaining walls take longer to build, but their “zest” is hidden in the reliability of the “armor.” The pressure of the adjacent soil on the retaining wall is dampened due to the considerable weight of the shield. To further strengthen them, the inner surface of the ground slab is made uneven: protrusions are formed in the monolithic concrete, and the brickwork is protruded inward. The outer side of the shield is inclined towards the slope. The required angle is determined by the formula:

Where j is the angle of natural repose for different types of soil.

The design of basement walls is carried out by analogy with the design of high retaining walls. Particular attention is paid to the reliability of the connection of the lower corners of the basement “box”.

On average, the height of the basement in a garage is up to 3 m (multiples of 0.6 m). For their construction, ready-made reinforced concrete blocks are used or slabs are poured directly on the construction site. Independent design retaining walls and basement walls of such heights are risky and dangerous. As mentioned above, the calculation algorithm is too complex for a person who does not have specialized knowledge. Only a specialist will correctly and accurately calculate the soil pressure at the required level and select the optimal parameters for the basement walls. The same applies to ways to strengthen them.

Chapter 7. CALCULATION AND DESIGN OF RETAINING WALLS

7.1. TYPES OF RETAINING WALLS

Retaining walls are divided into massive and thin-walled according to their design. The stability of massive retaining walls against shear and overturning is ensured by their own weight.

Retaining walls: calculation and classification

The stability of thin-walled retaining walls is ensured by the own weight of the wall and the soil involved in the work of the wall structure, or by pinching the walls into the base (flexible retaining walls and sheet piling).

The cross-sectional shapes of massive walls are shown in Fig. 7.1, thin-walled retaining walls of an angle profile - in Fig. 7.2 and 7.3.



7.1. Massive retaining walls

A- with two vertical edges; b- with a vertical front and inclined back edge; V- with an inclined front and vertical back edge; G- with two inclined edges on the side of the backfill; d- with a stepped rear edge; e- with a broken back edge

Massive and thin-walled walls can be constructed with an inclined base or with an additional anchor plate (Fig. 7.4).

Flexible retaining walls and sheet piling can be made from wooden, reinforced concrete and metal sheet piles of special profile. At low heights, cantilever walls are used; high walls are anchored by installing anchors in several rows (Fig. 7.5).



Rice. 7.2. Thin-walled corner retaining walls
A- console; b- with anchor rods; V- buttress



7.3. Pairing of front and foundation slabs
A- using a slotted groove; b- using a loop joint



Rice. 7.4. Prefabricated Retaining Walls
A- with anchor plate; b- with inclined sole



7.5. Schemes of flexible retaining walls
A- console; b- with anchors

Construction of buildings in large cities, when buildings are located over short distances, is always problematic. When digging a cave, it is very likely that the main structures of neighboring buildings, which were left without support from the ground, will begin to move.

The solution to this situation is a boring retaining wall. The fact is that they are boring, which are built in a row along the border of the foundation pit of a new house.

Specialists from PSK "Funds and Funds" offer the installation of fastening walls for long-distance pilots in Moscow, Moscow and other regions of the Russian Federation.

Considering that this type of pier foundation can be poured to a depth of up to 50 m, it becomes possible to build support walls for deep excavations, which will then be organized, for example, by several levels of parks.

Depending on the operating characteristics, pilots are durable structures that can replace a thick layer of soil. However, when choosing a size, there are several indicators to consider:

• soil type at the construction site;
• ground water level;
• the value of active pressure in the soil;
• its adhesion:
• and so on.

A retaining wall with boring pilots is one or more types of clusters that are poured into the ground at a specified distance, either in series or between rows.

Funds may be ordered or streamlined. In a load-bearing wall, all pilots must have the same depth and diameter.

To determine the distance between the beams, called the gap, you need to do some calculations.

Do you need a wall to keep boring pilots out?

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We include installation of all types of foundations and recommend the most suitable option depending on the construction conditions. And even in the shortest possible time, we will assemble the project and provide you with a ready-made estimate.

Calculation of a retaining wall

The diameter of the pilots must be at least 40 cm.

The specific indicator is calculated taking into account the land on the curve, taking into account the distance between the carriers and the base of the neighboring house and the type of soil. Therefore, preliminary geological studies are carried out at the construction site, which will show the type of soil.

An important indicator is the gap. When calculating the support walls from long pilots, we take into account two values:

1. Among the lines. This value should not exceed three bath diameters.

   For example, if the diameter of the support is 0.5 m, the distance between the rows should not exceed 1.5 m. Increasing the parameters, pressing the retaining wall against the bead support in the horizontal direction, creates the conditions for the last bend.

   Calculation of fixing walls

   This reduces the quality of the building.

2. Among clusters on the same line. Here we use a complex formula in which there are several values: b = 5.14 x LX C xD / E, where “I” is from the height of the passage, “C” is the value, “d” of the anti-slip platform is the diameter of the pile, “ e "- pressure on the ground (active).

The last formula is used in calculations if the floor is hard and durable at the construction site.

If the drilling process involves water or sediment, the distance should not be less than 0.7 m. If the pilots are designed without fixing or removing the housing wall, the distance between supports should be not less than 0.4 m.

The design of the retaining wall necessarily includes a mesh that connects all the supports, making the structure more secure and reliable.

This is a conventional concrete strip type structure that is attached to drill pilots. In the case of a one-stage fastening of the fixing wall from long piles, it is allowed to install the grid on supports.

As for the size of the zone structure, it depends entirely on the size of the pilots. However, there are certain standards that must be maintained when constructing a retaining wall.

• The minimum size of the belt pad relative to the brackets is 10 cm.
• The mesh height (minimum) is 20 cm.
• When building a wall in several types, the height of the saw structure is determined by the distance between the axes of the most distant beams, and here the stands stand in the horizontal load plane.

  Therefore, this parameter must be at least a quarter of this distance.

Wall structure fastening technology

The long-pilot retaining wall design is the standard construction of load-bearing wells by drilling the soil and overfilling the concrete solution. The sequence of work is as follows:

• Planning of pilots located along the excavation boundary is accomplished by accurately mapping drilling points.
• Drilling holes through one pile.

  Since the distance between the columns is not very large, it is impossible to drill two adjacent wells at the same time. The walls may collapse.

• Clean out the wells and fill them with sand.
• The frame is made of reinforced steel.
• The screws are filled with vibrations from concrete.
• Intermediate wells are drilled, reinforced and filled with concrete.
• The grate mounting frame is attached to brackets that are attached to the frame of the concrete shafts.

  Formwork and concrete are poured.

Concrete is fed into the recess through a perforated steel pipe, which gradually rises as the fountain fills. In some cases, the interior of the additional reinforcement cage remains.

Frame reinforcement

It is an important component in the construction of flight pilots.

The frame is made of a cylindrical shape made of reinforcement with a diameter of at least 10 mm. The length of the structure should be equal to the length of the bowl.

The choice between transverse reinforcement is selected taking into account the diameter of the pipe.

• If the diameter is in the range of 400-450 mm, the distance should be selected based on d / 2, but not more than 200 mm.
• If the diameter exceeds half a meter, the distance should be d/3, but not more than 500 mm.

The range between longitudinal reinforcements is 50-400 mm, taking into account the number of rods.

It must be at least 6 pieces.

Additional services

Drain groundwater and drainage walls that are constructed to carry out drainage or sewerage in the form of open ditches filled with sand, gravel or rock.

The length of the longitudinal inclination of the wall is 0.04. In the wall itself, every 3 m, you must install pipes through which moisture flows.

If the supporting wall is the boundary of a pedestrian terrace, it is used to install protective structures. The minimum height of the housing is 1 m.

The outer parts of the pilots must face the mounting technology of the mounting walls. It can be monolithic or prefabricated concrete, stone or any decorative material.

Flat, ground-facing pilots are waterproof. If there are no aggressive substances in the soil, waterproofing can be carried out using hot bitumen in two layers.

We install drilling, drilling, injection, drilling and pilot drilling

All work is turnkey!

We carry out all key work, from geological surveys to wiring devices.

Advantages of fastening walls from long pilots

The advantages of long pilots when using supporting walls are the following elements.

• Possibility of construction and reconstruction of the central part of the city, which is usually under frequent construction.
• Possibility of constructing multi-storey buildings with the need to develop underground space.
• Ensuring the reliability and stability of the walls of excavated excavations during the construction of main and overlapping structures.
• The technology for installing fastening walls made of long pilots makes it possible to completely eliminate uneven drainage of the foundations of adjacent buildings and structures.

  This eliminates emergencies.

• This technology is economically feasible and feasible.
• Possibility of building buildings on all types of soil.

How to order a fastening wall made of long piles from our company?

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Design features of retaining walls

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2.1. Massive walls .

V)	G)
d)

1 Types of Massive Retaining Walls

a - rectangular, b - in the form of a parallelogram, c - triangular, d - curvilinear, e - sloped

Rectangular or in the form of a parallelogram.

As a rule, these walls are economically justified only at very small heights (up to 2-3 m), while walls with a cross-section in the form of a parallelogram are more economical due to the reduction in backfill soil pressure on the wall (Fig. 1.a). The angle of inclination of the wall is selected from the condition of the stability of the wall without backfill.

7.3.3. Calculation of the foundations of retaining walls based on deformations

At the same time, when using inclined walls, part of the usable space is lost.

Triangular or trapezoidal.

These walls can have an inclined front or rear edge, or both inclined edges (Fig. 1.b,c). Profiles with a rear inclined edge are more economical, since in them the soil above the rear edge participates in increasing the stability of the wall.

Walls with curved or stepped edges.

The thickness of walls of this type at each height corresponds to the pressure intensity of a pound of backfill (Fig. 1.d). These walls, also called “pressure curve” walls, are the most economical, but they are more complex to manufacture and have less use of usable space.

Walls slopes or recumbent type.

Such walls, located on a natural slope and practically not experiencing pressure from the backfill, have limited use due to the large loss of usable space (Fig. 1.e).

Most often they are used as all kinds of fastenings for steep slopes against erosion and mechanical damage.

Thin-walled structures.

By design features walls of this type are divided into corner (Fig. 2) and buttress (Fig.

Corner retaining walls are the simplest and most commonly used design. The wall itself is the vertical shelf of the corner, which absorbs the horizontal pressure of the backfill soil.

The horizontal flange of the corner faces the backfill and, under the influence of the weight of the backfill soil, ensures the overall stability of the wall. Corner walls are made of both monolithic and precast reinforced concrete. In the case of a prefabricated design, the foundation slab has a grooved part into which the vertical (front) slab is embedded.

The dimensions and shape of the groove allow the foundation slab to be installed with an inclination (up to 7-9 degrees) towards the backfill, which increases the stability of the wall.

The selection of the section of the vertical slab of the corner wall is made on the basis of calculating it as a cantilever beam, pinched at the bottom and under the influence of the horizontal pressure of the backfill soil, the temporary load on its surface and the own weight of the wall.

The foundation slab is calculated as a cantilever beam loaded with the weight of 1 backfill soil and the reaction pressure (resistance) of the foundation soil. The width (overhang) of the foundation slab is determined from the condition of ensuring the stability of the wall against overturning and shear along the base.

Due to the fact that the ultimate shear resistance of soft clay soils is not high, the overhangs of the foundation slabs of corner walls located on such foundations are usually very large (0.8-1.0 of the wall height).

To reduce this size, a wall design with a foundation slab having an inclined console is often used, the introduction of which significantly reduces the active soil pressure on the wall.

In general, corner walls with a smooth facing vertical slab are generally economically feasible at heights of 5-8 m.

At higher heights, the pound pressure on the vertical part of the wall increases significantly, which leads to an increase in the size of sections, volumes of reinforced concrete and, accordingly, to a high cost of the structure.

2 Monolithic retaining wall

Buttress retaining walls (Fig. 3).

Walls of this type are economically justified at heights greater than 8-10 m, usually consisting of 3 main elements: vertical slab, foundation slab and buttress.

The distance between the buttresses is assumed to be 2.5-3 m. The introduction of buttresses into the wall structure, connecting the front and foundation slabs, significantly facilitates the conditions for their static operation, since in the presence of buttresses the foundation and front slabs work as continuous multi-span beams or as slabs , supported along the contour.

At the same time, the thickness of these wall elements is significantly reduced, which leads to a reduction in the volume of reinforced concrete and a reduction in the cost of the structure as a whole.

Buttresses work and are calculated as consoles with a T-section of variable height along the wall, loaded with horizontal and vertical loads transmitted from the front and foundation slabs.

Reinforcement of a buttress, as a rule, is carried out in three directions: horizontal and vertical - for reaction forces from the slabs, and also in an inclined direction (along the back edge of the buttress) - for bending moment.

Buttress walls can be made either monolithic or prefabricated.

In the case of a prefabricated design, the rigidity of the connection of wall elements is ensured by embedding them in specially arranged grooves.

Combined retaining walls may have different designs.

Combined walls with unloading platforms (Fig. 3.a) located on the wall from the backfill side are widespread. Unloading platforms, horizontal or inclined, significantly reduce the soil pressure of the backfill, which leads to a reduction in both the transverse and overall dimensions of the wall.

The overhang of unloading platforms when they are designed in the form of a cantilever is usually taken to be no more than 20-25% of the total height of the wall. If it is necessary to increase the reach of the unloading platform, various support devices are used that reduce bending moments not only in the platform itself, but also in the front wall slab.

3 Types of combined retaining walls

a - with an unloading platform, b - with a screen, c - with a sail element.

Combined retaining walls also include structures with shielding devices (Fig. 3.b) placed in the backfill directly behind the wall. Shielding devices (usually in the form of one or several rows of piles or sheet pilings) lead to a decrease in the backfill soil pressure on the wall and an increase in its stability.

At the same time, the significant complication of the technology for constructing such walls leads to the need for a feasibility study of the feasibility of their use in each specific case.

The desire to effectively use high-strength and cheap artificial materials in construction led to the creation of sail-type retaining walls (Fig. 3.c). The main structural elements of such combined walls are a flexible sail made of fiberglass or fiberglass, free-standing pile supports and horizontal anchor plate.

The sail, working under the action of the tensile soil pressure of the backfill, transfers only an axial compressive force to the piles, and only a shear force to the anchor plate.

The noted “separation” of forces transmitted to structural elements makes it possible in some cases to make the wall more economical compared to conventional structures. At the same time, the increasing complexity of work technology, as well as significant losses of usable space, limit the use of this type of structure.

Flexible retaining walls.

Bolver walls(Fig. 4.a) are the foundations of a structure significantly buried in the ground, the strength of which is ensured by resistance to bending, and stability by the resistance of the foundation soil to uplift.

The main elements of the bolts are sheet pilings or piles driven into the soil of the base and thin-walled slabs covering the gap between the driving elements, forming the front face of the wall. Such designs are economically justified at heights up to 4-5 m.

A)

b)

4 Flexible retaining walls

a - bolt-on, b - anchor-bolver.

When the wall height is more than 5-7 m, in order to reduce the cross-section of the load-bearing driving elements, well-working tensile rods are attached to the upper part of the wall, connecting these elements with special anchors placed in the backfill soil outside the collapse prism (Fig. 4).

Such walls are called anchor-bolverkovymi. Anchor rods can be located in one or several tiers along the height of the wall. They transfer the load from the backfill soil (perceived by the upper part of the wall) to the anchor devices and, as a rule, work only in tension; the rods are made of steel or reinforced concrete.

Anchor devices are beams, slabs or blocks buried in the ground.

Structurally interesting and, as a rule, economically justified in a wide range of heights (5-30 m) are fully anchored retaining walls of the type "reinforced soil".

Walls of this type (Fig.

5) consist of an external cladding, flexible reinforcing elements connected to the cladding, and soil poured over the reinforcing elements to the entire height of the wall. The external cladding can be made of either corrugated steel sheets (2-4 mm thick) or flat reinforced concrete elements 20-25 mm thick.

The economic efficiency of retaining walls made of reinforced soil increases as their height increases and, with a design height of 20-25 m, reaches 40-50% compared to conventional walls made of reinforced concrete.

5 Retaining wall type "reinforced soil"

List of used literature

1. DSTU B A.2.4-4:2009. Main benefits for design and work documentation: –K. Ministry of Regional Development of Ukraine, 2009. – 51 p.

5. DBN V.1.2-2:2006. Navantazhennya ta vplivi. Standard design. / Ministry of Buddhism of Ukraine. – K. 2006.

6. DBN V.2.6-158:2009. The designs were made and spores. Concrete and reinforced concrete structures with important concrete.

Design rules. Ministry of Buddhism of Ukraine. -TO. 2010.

7. DBN V.2.6-160:2010. The designs were made and spores. Steel-concrete structures. Basic provisions. Ministry of Buddhism of Ukraine. -TO. 2010.

8. DBN V.2.6-161:2010. The designs were made and spores. Wooden structures. Basic provisions. Ministry of Buddhism of Ukraine. -TO. 2011.

9. DBN V.2.6-162:2010. The designs were made and spores. Stone and armored stone structures.

Basic provisions. Ministry of Buddhism of Ukraine. -TO. 2011.

10. DBN V.2.6-163:2010. The designs were made and spores. Steel structures. Standards for design, manufacturing and installation. Ministry of Buddhism of Ukraine. -TO. 2011.

11. Designer's reference. Typical reinforced concrete structures of booths and equipment for industrial activities. M.: Stroyizdat, 1981.- 378 p.

Mandrykov A.P. Apply the reinforcement to the reinforced concrete structures. M.: Stroyizdat, 1989. - 506 p.

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After creating the dimensions of the retaining wall consoles and clicking the Next button, the Retaining Wall - Reinforcement dialog box appears on the screen.

Options for creating retaining wall reinforcement are found on two tabs in the dialog box.

The first tab is shown in the figure above. The main reinforcement of a retaining wall can be created using:

• reinforcing bars;
• reinforcing bars and wire mesh.

At the top of the dialog box, the following vertical reinforcement parameters can be created:

After completing the definition of the main reinforcement of the retaining wall and clicking on the Next button, the dialog box shown below appears on the screen. This is the second embed used to create the retaining wall reinforcement.

The following parameters can be defined at the bottom of the dialog box:

The units of measurement used to create the geometry and reinforcement of a reinforced concrete pile are configured in the Work Settings dialog box.

At the bottom of the dialog box there are selection lists that allow you to define the hierarchy of created projects and templates; the following rules apply:

• in the hierarchy, the project is the highest component of the group;
• several different groups can be created in a project;
• each group can include many templates.

This hierarchy makes it easier to manage the design elements included in a project. It is also easier to copy a project between two users (computers used by users) - just copy the entire folder with the project name for the entire project hierarchy with all groups and templates.

The user can define an arbitrary hierarchy. The following hierarchy can be used as an example:

• Project – Structures;
• Group - Foundations;
• Template - Retaining wall 01.

The Templates list includes templates (schemes) of retaining walls and their reinforcement created by the user.

After determining the geometric characteristics of the retaining wall and its reinforcement, you can save these parameters by specifying a name in the Template field and clicking the Save button ( Note: the template is saved in the selected group and selected project). Later, when creating reinforcement for a retaining wall, after selecting the name of the saved template (in the selected group and selected project); all parameters in the dialog box will be exactly the same as they were saved in the template.

When you click the Load button, the template saved in the selected project and selected group opens. Below is the Delete button. If you click on it, the selected template in the selected project and selected group will be deleted.

The saved templates are available in macros for formwork elements and they can be loaded with the corresponding reinforcement macros.

Once the template is loaded, on the Geometry tab the program will configure the structural element geometry parameters saved in the template.

At the bottom of the dialog box are the following buttons.

• Preview – you can preview the retaining wall and its reinforcement;
• Back< / Далее >– opens the previous/next bookmark;
• Insert – the created retaining wall and its reinforcement are inserted into the drawing.

  It is necessary to indicate the reinforcement position number and the location of the created element in the drawing. Along with the retaining wall drawing, the program also inserts a reinforcement specification in accordance with the settings in the Work Settings dialog box.

Federal State Budgetary Educational Institution

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Department of "Building structures"

on the topic of: ".

Construction technology. Features of operation"

in the discipline: “Special sections of technical mechanics”

Introduction

Modern types of retaining walls

Box gabions

Gabions with diaphragms

Mattress gabions

Cylindrical gabions

Retaining walls made of textile reinforced soil

Geogrid

Retaining walls made from waste tires

Retaining walls made of metal mesh

Terramesh system

System "Green Terramesh"

Macwall system

Conclusion

Introduction

Often the plots are located on slopes, slopes of ravines, and on river banks.

Often, after construction work, artificial relief is formed on the site. The layout of such a garden will require the arrangement of horizontal surfaces for planting, but completely leveling the surface is impractical, so the terracing method is used. Terracing a site is the formation of horizontal ledges (terraces) reinforced with retaining walls. This design solution will help protect the land from soil erosion, and retaining walls will prevent soil erosion.

Retaining walls perform both practical and decorative functions.

On a site with a slope or complex terrain, they allow terracing; on a flat surface, low retaining walls can highlight part of a raised garden. This will give the site a unique relief and volume and make it more visually interesting. The choice of material, configuration and dimensions of the retaining wall depend on the concept of the garden.

Any retaining wall consists of the following parts:

The foundation is the part of the wall that is located underground and bears the main load from soil pressure.

The body is the vertical part of the structure (the wall itself).

Drainage is a drainage system necessary to strengthen the strength of the wall.

<#»justify»>Modern types of retaining walls

A gabion is a gravitational (providing stability on the ground due to its own mass) structure, which is a spatial rectangular or cylindrical shape, consisting of a durable metal mesh filled natural stone.

The main types of gabion structures include:

box gabion;

gabion with diaphragms;

mattress gabion;

cylindrical gabions (bags).

Note: All types of gabions use a double torsion mesh with a diameter of 2.7 and 3 mm with a zinc or galfan coating, filled with natural stone (crushed stone, pebbles, cobblestones, etc.). The grid consists of hexagonal cells 10x12, 8x10, 6x8 or 5x7 cm.

In aggressive environments, a polymer (PVC) mesh coating is additionally used. Double torsion of the wire mesh ensures integrity, strength and uniform distribution of loads, and prevents the wire from unwinding in the event of a mesh break. The wire for gabions, as well as the mesh made from it, must comply with GOST R 51285-99 “Twisted wire mesh with hexagonal cells for gabion structures”

Gabions are widely used for landscaping private suburban areas - construction of retaining walls, strengthening the banks of reservoirs, watercourses and other works on engineering protection and landscaping of territories

Box gabions

Gabion is a rectangular spatial box-shaped structure consisting of a metal mesh filled with natural stone (crushed stone, pebbles, cobblestones, etc.).

Box gabion block.

Gabions (blocks) are tied together with wire, resulting in a flexible retaining wall. Such a wall compares favorably with analogues made of concrete and reinforced concrete and allows you to rationally solve a number of engineering and landscape problems:

no special foundation or foundation is required;

are built quickly and at any time of the year;

drainage is carried out due to the porosity of the block, the structure freely passes water through itself;

the ability to absorb sudden and localized loads caused by large precipitation or ground deflections due to the flexibility of the entire structure.

In this case, destruction of the gabion structure itself does not occur;

increasing the efficiency of gabion structures over time, as the gabion voids are filled with soil in which vegetation grows, holding the stone backfill together with its root system;

easy to install in places hard to reach for construction equipment;

useful areas for planting are preserved;

gabion structures do not interfere with the growth of vegetation and blend into the environment.

Over time, they become natural blocks of green that enhance the landscape.

Installation of gabions is carried out in the following sequence:

installing a metal mesh container on a prepared base (simple horizontal leveling of the surface is sufficient);

connecting gabions together with galvanized wire;

laying stone, such as flagstone, carefully along the front side of the container.

Filling the remaining volume with crushed stone, pebbles, cobblestones, etc. (up to 90% of the total volume).

Note: Over time, the free volume is filled with soil particles and the gabion structure is completely consolidated, after which it acquires maximum stability and can serve indefinitely.

installation of containers, like a wall of cubes, to the required height and length of the wall.

Fastening containers together with galvanized wire. Filling them with stone;

final connection with wire of all the constituent elements of the structure.

Note: A geotextile filter (thermally bonded geotextile) can be installed on the inside of the gabion (from the backfill soil side) instead of traditional sand and gravel filters.

Material - galvanized wire 2.7/3.0mm or PVC coated wire 3.7/4.4mm.

Gabions with diaphragms

Gabions with diaphragms differ from box gabions in their geometric dimensions.

They are flat mesh structures in the shape of a parallelepiped, 0.5 m high and with a large base surface area. The internal volume is divided into sections (1 m in length) using mesh diaphragms.

Gabions are used in the base of box-shaped gabion retaining walls, as well as in landscape work.

At the same time, they serve as a protective apron that protects the base of the structure from erosion.

Mattress gabions

Mattresses are rectangular structures with a large area and small height, usually from 17 to 50 cm.

Mattresses (mattresses) got their name from the small ratio of height to length and width.

For strength, long-length mattresses are also internally divided by transverse diaphragms (every 1 m) to ensure the rigidity of the mesh structure.

They are filled with stones, forming a monolithic structure.

Mattresses are used as a base for retaining walls made of box-shaped gabions, protect the base of the structure from erosion, protect and stabilize the soil from erosion.

Mattress gabions.

Cylindrical gabions (bags)

Cylindrical structures made of metal mesh, filled with natural stone.

For strength, long boxes are divided internally by transverse diaphragms. Cylindrical gabions are indispensable when constructing retaining walls near reservoirs as underwater foundations.

Dimensions of cylindrical gabions.

Wire diameter 2.7-3.0 mm

Cylindrical gabion

Retaining walls made of soil reinforced with geotextiles

A technology for constructing a retaining wall from soil reinforced with synthetic materials has been developed and is being used. Geotextile panels are used for external cladding and wall reinforcement. The wall construction technology consists of the following sequence of work:

To construct the wall layer, formwork is installed from steel corner elements and wooden posts with a height exceeding the thickness of the soil layer.

The pitch of the formwork elements is 1.5 m;

after installing the formwork, geotextile panels of a length determined by calculation are laid on top of it and the lower compacted layer of soil;

the free outer edge of the geotextile is thrown outward over the formwork. Then a layer of bulk soil is laid (approximately 1.2 m across the width of the wall) and thoroughly compacted;

The free edge of the geotextile is turned back and laid on top of the compacted soil.

Then the rest of the soil layer is poured in and compacted. The next layer is laid with a slope of 2% across the width of the structure to ensure its stability;

then the formwork is removed and transferred to the top of the laid layer. The main purpose of the formwork is to ensure that the corners of the outer lining are densely filled with soil during compaction.

To protect polypropylene-based geotextile exterior cladding from ultraviolet rays, it can be covered with a layer of shotcrete, a bitumen coating, or lined with wood, or covered with soil and outdoor landscaping.

The physical and mechanical characteristics of geotextiles must correspond to the loads acting on the wall.

The range of geotextile brands is quite wide, both domestically produced and imported.

Retaining walls built using this technology have the necessary strength, are economical in construction and are quite durable. Retaining walls constructed from soil reinforced with geogrids in combination with geotextiles have proven themselves well in operation.

Such walls are maximally adapted to uneven precipitation and compensate for temperature and shrinkage stresses.

Geogrid

Geogrid is a reinforcing geotechnical material. It is a set of sheet strips, thickness from 1.35 mm to 1.8 mm and height from 50 to 200 mm. The sheet strips are connected by seams to each other throughout their entire depth, forming geogrid cells.

The depth and dimensions of the cells are selected depending on the design criteria of the load and the structure of the filler materials.

When deployed, the geogrid forms a cellular structure, which is filled with mineral filler. Geogrid sections have high physical and mechanical characteristics and can withstand temperature conditions of all climatic zones.

Geogrid sections are made from durable and at the same time flexible polyethylene tapes, which allows the construction of retaining walls of various configurations in areas with any terrain.

The steepness of the slope being strengthened is not limited and can be vertical.

Retaining wall calculation

The retaining wall is a multi-layer tiered structure with geogrids arranged one above the other. In this case, geogrids are laid with a horizontal shift relative to each other or without a shift. Geogrids are filled with sandy soil with the addition of stone materials and covered with geotextile panels.

To fill geogrid cells, it is possible to use local soils, taking into account that the backfill material must have good drainage properties.

The outermost, free cells (when tiers shift) are filled with plant soil, followed by sowing grass seeds.

Sprouted grass will further strengthen the surface of the retaining wall and decorate the overall landscape.

The main advantages of such retaining walls:

increasing (or ensuring) the reliability and durability of the structure;

reduction of material consumption;

reducing the cost of structures;

improving manufacturability and quality of work

Geogrid installation technology for almost all types of soil strengthening (cones and slopes of the subgrade and associated soil structures) includes the following operations:

preparing an inclined or vertical surface by leveling, compacting or installing it;

installation of additional elements in the form of laying geotextiles;

laying out geogrid sections and joining them together with staples using a stapler;

fastening the geogrid to the ground with metal or plastic anchors to ensure longitudinal and lateral stability;

filling volumetric cells various materials(soil, crushed stone).

Sowing vegetation into cells (with a horizontal shift), for example, using hydroseeding.

Installation of geogrids does not require high qualifications and is performed manually.

Retaining walls made from waste tires

A new technology for constructing retaining walls from waste tires is coming into practice. In this case, the retaining walls are strong enough to keep large masses of soil from sliding down the slope. The cost of such walls is significantly lower compared to traditional methods, and construction time is reduced.

An analysis of the effectiveness of a retaining wall made from worn tires showed their cost-effectiveness: 10 times cheaper and 9 times less labor intensive than a wall made of reinforced soil and a third cheaper than traditional concrete retaining walls.

When constructing such retaining walls, the following options are used:

The coating is assembled from car tires, located in steps along the slope and mounted on vertically installed piles.

Tires are attached to the piles as follows. The lower tires mounted on the piles rest against the piles with one edge of the inner diameter on the side of the slope, and the tires of the upper rows with their opposite edge of the inner diameter are attached to the piles using flexible clamps. The intermediate tires are loosely mounted on piles, fastened together, and connected to the upper and lower tires by means of filler (cobblestone) located in their cavities.

Fastenings in the form of strips made from a conveyor belt fastened with bolts are used as fastening materials (clamps) for bus modules.

Columns are formed from one, two or more rows of tires.

For stability, anchor piles are driven in the center of the columns. The tires are then filled (with tamping) with local soil. The tires are secured in rows with clamps.

A wall is made from tires with one side wall cut out. Soil is compacted into the bottom row (to the top). Durable sheet material is laid on this row to prevent spillage of soil from the row of tires located above. Subsequent rows of tires are laid in the form of brickwork (in a sling).

Their cavities are also filled with soil. Anchor piles (pins) are driven into the outside of the wall to support the bottom row and prevent horizontal displacement of the wall.

The tires are attached to each other both in a row and between rows using plastic wire or propylene ropes.

The heavier the filling soil, the more stable the retaining wall.

The frequency (step) of fastening the tires to each other is determined depending on the geometric parameters of the retaining wall.

Retaining walls made of metal mesh

A simplified design of retaining walls made of metal mesh has been developed and used.

The retaining wall itself is a structure buried in the ground. metal pipes with an inclination towards the slope, to which a high-strength metal mesh with an anti-corrosion coating is attached using metal wire.

Gravel is poured between the mesh and the retained soil, with a fractionation greater than the cell size.

The design of such a wall is clearly visible in the photographs shown.

Technologies for constructing retaining walls

retaining wall gabion structure

The first stage of constructing a retaining wall is digging a pit for the foundation.

In dry soils a strip foundation is used, in swampy soils a pile foundation is used. The thickness of the foundation should be 150-200mm greater than the thickness of the masonry of the wall body. The foundation is laid on a bed of well-compacted crushed stone of fine fractions, separated from the parent soil by a layer of geotechnical textiles. The thickness of the pillow must be at least 50mm. The entire foundation is placed 150mm below ground level.

Regardless of the material of manufacture, the construction of a retaining wall ends with the installation of a drainage system on the side of the supported soil.

The system is built from layers of geotechnical textiles and coarse sand or fine gravel between them. The thickness of the gravel layer is 70-100mm. A drainage layer is laid in parallel with the construction of the embankment.

The soil at the base of the retaining walls is reinforced with either a layer of turf or geogrids.

Such a well-built retaining wall will serve reliably and for a long time.

Terramesh system

Retaining walls<#»171″ src=»doc_zip10.jpg» />

Double torsion of the mesh, which is the starting material, guarantees uniform distribution of loads, integrity, strength, and also prevents untwisting in the event of a local rupture of the mesh.

Gabions, such as the Terramesh System, are environmentally friendly modular soil reinforcement systems used for slope strengthening<#»justify»>Green Terramesh System

The Green Terramesh gabion system is a modular design for soil reinforcement<#»208″ src=»doc_zip12.jpg» /> <#»195″ src=»doc_zip13.jpg» /> <#»234″ src=»doc_zip14.jpg» /> <#»164″ src=»doc_zip15.jpg» /> <#»164″ src=»doc_zip16.jpg» /> <#»164″ src=»doc_zip17.jpg» /> <#»164″ src=»doc_zip18.jpg» /> <#»justify»>Conclusion

Retaining walls solve an important problem in areas with uneven surfaces.

When developing landscaping projects, the terracing method is often used, since many areas have complex, uneven terrain. The construction of retaining walls helps solve this problem, the main task of which is to keep the soil from sliding from the upper part of the terrace to the lower one. In addition, retaining walls give the site its unique appearance and well-groomed appearance.

Retaining walls can be completely different in design and depend most on the height of the terrace. With a small height of retaining walls, you can do without a foundation.

The material for constructing retaining walls can be not only concrete or natural stone, but also many other materials such as wood, brick and others. Retaining walls made of natural stone, brick or wood usually do not exceed one meter in height.

When landscape planning, the use of retaining walls is almost mandatory, because this multifunctional element allows you to prevent landslides, which are common near lakes and rivers, and sometimes even ponds.

If the site is adjacent to a ravine, retaining walls make it possible to reliably strengthen the slopes, saving the owner of the site from many troubles.

In addition to their direct purpose - to prevent the soil from sliding - retaining walls help in the rational use of garden space and help create favorable conditions for the growth of trees and shrubs.

Bibliography

Budin A.Ya. Thin retaining walls. L.: Stroyizdat, 1974. 191 p.

Korchagin E.A. Optimization of retaining wall designs. M.: Stroyizdat. 1980.116 p.

Klein G.K. Calculation of retaining walls. M.: Higher School, 1964. 196 p.

Design Guide for Retaining Walls and Basement Walls for Industrial and Civil Engineering.

M.: Stroyizdat, 1984.115 p.

Directory of engineering structures designer. Kyiv: Budivelnik, 1988. 352 p.

Saglo V.V., Sviridov V.V.

Experience in the construction of retaining walls on the Northern Railway // Tez. report 2nd Int. scientific-technical conf. “Current problems of railway development. transport". In 2 volumes. Volume 1. Ministry of Railways of the Russian Federation. MSU PS. M., 1996. p. 75.

Sviridov V.V. Slope stability. Part 1. Soil slopes: Textbook. RGUPS. Rostov n/d, 1994. 26 p.

Sviridov V.V. Slope stability. Part 2. Rock slopes: Textbook. RSU PS. Rostov n/d, 1995. 39 p.

Sviridov V.V. Reliability of foundations and foundations (mathematical approach): Textbook.

RGUPS. Rostov n/d, 1995. 48 p.

Sviridov V.V. Ensuring the reliability of retaining walls. Proceedings of the All-Russian Scientific and Technical Conference. Part 1. Fundamental and applied research “Transport 2000”. Ekaterinburg. 2000. p. 313 - 314.

Tags: Modern types of retaining walls. Construction technology. Features of operation Abstract Construction

CENTRAL RESEARCH FACILITY

AND DESIGN AND EXPERIMENTAL INSTITUTE OF INDUSTRIAL BUILDINGS AND STRUCTURES (TsNIIPromzdanii) GOSSTROY OF THE USSR

REFERENCE MANUAL

Design of retaining walls

and basement walls

Developed for “Construction of industrial enterprises”. Contains basic provisions for the calculation and design of retaining walls and basement walls of industrial enterprises made of monolithic and prefabricated concrete and reinforced concrete. Calculation examples are given.

For engineering and technical workers of design and construction organizations.

PREFACE

The manual is compiled for “Constructions of industrial enterprises” and contains the basic provisions for the calculation and design of retaining walls and basement walls of industrial enterprises made of monolithic, prefabricated concrete and reinforced concrete with calculation examples and the necessary tabular values ​​of coefficients that facilitate the calculation.

In the process of preparing the Manual, certain calculation prerequisites were clarified, including taking into account soil adhesion forces, determining the inclination of the sliding plane of the collapse prism, which are supposed to be reflected in the addition to the specified SNiP.

The manual was developed by the Central Research Institute of Industrial Buildings of the USSR State Construction Committee (candidates of technical sciences A. M. Tugolukov, B. G. Kormer, engineers I. D. Zaleschansky, Yu. V. Frolov, S. V. Tretyakova, O. J. Kuzina) with the participation of NIIOSP them. N. M. Gersevanova of the USSR State Construction Committee (Doctor of Technical Sciences E. A. Sorochan, Candidates of Technical Sciences A. V. Vronsky, A. S. Snarsky), Foundation of the Project (engineers V. K. Demidov, M. L. Morgulis, I.S. Rabinovich), Kiev Promstroyproekt (engineers V.A. Kozlov, A.N. Sytnik?? N.I. Solovyova).

1. GENERAL INSTRUCTIONS

1.1. This Manual is compiled for “Constructions of industrial enterprises” and applies to the design of:

retaining walls erected on a natural foundation and located in the territories of industrial enterprises, cities, towns, access and on-site railways and roads;

basements for industrial purposes, both free-standing and built-in.

1.2. The manual does not apply to the design of retaining walls of main roads, hydraulic structures, special-purpose retaining walls (anti-landslide, anti-landslide, etc.), as well as to the design of retaining walls intended for construction in special conditions (on permafrost, swelling, subsidence soils, on undermined territories, etc.).

1.3. The design of retaining walls and basement walls should be based on:

master plan drawings (horizontal and vertical layout);

report on engineering and geological surveys;

technological specification containing data on loads and, if necessary, special requirements for the designed structure, for example, requirements for limiting deformations, etc.

1.4. The design of retaining walls and basements should be established on the basis of a comparison of options, based on the technical and economic feasibility of their use in specific construction conditions, taking into account the maximum reduction in material consumption, labor intensity and construction costs, as well as taking into account the operating conditions of the structures.

1.5. Retaining walls constructed in populated areas should be designed taking into account the architectural features of these areas.

1.6. When designing retaining walls and basements, design schemes must be adopted that provide the necessary strength, stability and spatial invariability of the structure as a whole, as well as its individual elements at all stages of construction and operation.

1.7. Elements of prefabricated structures must meet the conditions for their industrial production at specialized enterprises.

It is advisable to enlarge the elements of prefabricated structures, as far as the load-carrying capacity of the mounting mechanisms, as well as the manufacturing and transportation conditions allow.

1.8. For monolithic reinforced concrete structures, standardized formwork and overall dimensions should be provided, allowing the use of standard reinforcement products and inventory formwork.

1.9. In prefabricated structures of retaining walls and basements, the design of units and connections of elements must ensure reliable transmission of forces, the strength of the elements themselves in the joint area, as well as the connection of additionally laid concrete at the joint with the concrete of the structure.

1.10. The design of structures for retaining walls and basements in the presence of an aggressive environment must be carried out taking into account the additional requirements of SNiP 3.04.03-85 “Protection of building structures and structures from corrosion.”

1.11. The design of measures to protect reinforced concrete structures from electrocorrosion must be carried out taking into account the requirements of the relevant regulatory documents.

1.12. When designing retaining walls and basements, one should, as a rule, use unified standard structures.

The design of individual structures of retaining walls and basements is allowed in cases where the values ​​of the parameters and loads for their design do not correspond to the values ​​​​accepted for standard structures, or when the use of standard structures is impossible based on local construction conditions.

1.13. This Manual considers retaining walls and basement walls backfilled with homogeneous soil.

2. MATERIALS OF CONSTRUCTION

2.1. Depending on the design solution adopted, retaining walls can be built from reinforced concrete, concrete, rubble concrete and masonry.

2.2. The choice of structural material is determined by technical and economic considerations, durability requirements, work conditions, the availability of local building materials and mechanization equipment.

2.3. For concrete and reinforced concrete structures, it is recommended to use concrete with a compressive strength of at least class B 15.

2.4. For structures subject to alternating freezing and thawing, the design must specify the grade of concrete for frost resistance and water resistance. The design grade of concrete is established depending on the temperature conditions that arise during the operation of the structure and the values ​​of the calculated winter temperatures of the outside air in the construction area and is accepted in accordance with Table. 1.

Table 1

	Calculated	Concrete grade, not lower
designs	temperature	by frost resistance	by water resistance
freezing at	air, ??C	Structure class
alternating freezing and thawing
In water-saturated
condition (for example, structures located in a seasonally thawing layer							Not standardized
soil in permafrost areas)	Below -5 to -20 inclusive					Not standardized
					Not standardized
In conditions of occasional water saturation (for example, above-ground structures that are constantly exposed to							Not standardized
weather conditions)	Below -20 to -40 inclusive					W2 He is normalized
	Below -5 to -20				Not standardized
	inclusive
Under air-humidity conditions in the absence of episodic water saturation, for example,							Not standardized
structures, permanently (exposed to ambient air, but protected from atmospheric precipitation)	Below -20 to -40 inclusive				Not standardized
	Below -5 to -20 inclusive

* For heavy and fine-grained concrete, frost resistance grades are not standardized;

** For heavy, fine-grained and lightweight concrete, frost resistance grades are not standardized.

Note. The estimated winter outside air temperature is taken as the average air temperature of the coldest five-day period in the construction area.

2.5. Prestressed reinforced concrete structures should be designed primarily from class B 20 concrete; At 25; B 30 and B 35. For concrete preparation, class B 3.5 and B5 concrete should be used.

2.6. The requirements for rubble concrete in terms of strength and frost resistance are the same as for concrete and reinforced concrete structures.

2.7. For reinforcement of reinforced concrete structures made without prestressing, hot-rolled reinforcing steel bars of periodic profile of class A-III and A-II should be used. For installation (distribution) fittings, it is allowed to use hot-rolled reinforcement of class A-I or ordinary smooth reinforcing wire of class B-I.

When the design winter temperature is below minus 30°C, class A-II reinforcing steel of grade VSt5ps2 is not allowed for use.

2.8. As prestressing reinforcement for prestressed reinforced concrete elements, thermally strengthened reinforcement of class At-VI and At-V should generally be used.

It is also allowed to use hot-rolled reinforcement of class A-V, A-VI and thermally strengthened reinforcement of class At-IV.

When the design winter temperature is below minus 30°C, reinforcing steel of class A-IV grade 80C is not used.

2.9. Anchor rods and embedded elements must be made from rolled strip steel class C-38/23 (GOST 380-88) grade VSt3kp2 at design winter temperatures up to minus 30°C inclusive and grade VSt3psb at design temperatures from minus 30°C to minus 40° WITH. For anchor rods, steel S-52/40 grade 10G2S1 is also recommended at design winter temperatures up to minus 40°C inclusive. The thickness of the strip steel must be at least 6 mm.

It is also possible to use class A-III reinforcing steel for anchor rods.

2.10. In prefabricated reinforced concrete and concrete structural elements, mounting (lifting) loops must be made of reinforcing steel class A-I brands VSt3sp2 and VSt3ps2 or from steel class Ac-II grade 10GT.

When the estimated winter temperature is below minus 40°C, the use of VSt3ps2 steel for hinges is not allowed.

3. TYPES OF RETAINING WALLS

3.1. According to their design, retaining walls are divided into massive and thin-walled.

In massive retaining walls, their resistance to shear and overturning under the influence of horizontal soil pressure is ensured mainly by the wall’s own weight.

In thin-walled retaining walls, their stability is ensured by the wall’s own weight and the weight of the soil involved in the work of the wall structure.

As a rule, massive retaining walls are more material-intensive and more labor-intensive to construct than thin-walled ones, and can be used with an appropriate feasibility study (for example, when they are built from local materials, the absence of precast concrete, etc.).

3.2. Massive retaining walls differ from each other in the shape of the transverse profile and material (concrete, rubble concrete, etc.) (Fig. 1).

Rice. 1. Massive retaining walls

a - c - monolithic; g - e - block

Rice. 2. Thin-walled retaining walls

a - corner console; b - corner anchor;

c - buttress

Rice. 3. Pairing of prefabricated front and foundation slabs

a - using a slotted groove; b - using a loop joint;

1 - front plate; 2 - foundation slab; 3 - cement-sand mortar; 4 - embedment concrete

Rice. 4. Retaining wall design using universal wall panel

1 - universal wall panel (UPS); 2 - monolithic part of the sole

3.3. In industrial and civil construction, as a rule, thin-walled corner-type retaining walls shown in Fig. are used. 2.

Note. Other types of retaining walls (cellular, sheet piling, shell, etc.) are not considered in this Manual.

3.4. According to the manufacturing method, thin-walled retaining walls can be monolithic, prefabricated or precast-monolithic.

3.5. Thin-walled cantilever walls of the corner type consist of front and foundation slabs, rigidly interconnected.

Project documentation- documentation containing text and graphic materials and defining architectural, functional-technological, structural and engineering solutions to ensure the construction and reconstruction of capital construction projects.

Types of work on the preparation of project documentation that affect the safety of capital construction projects should be performed only by individual entrepreneurs or legal entities that have certificates of admission to such types of work issued by a self-regulatory organization. Other types of work on the preparation of project documentation can be performed by any individuals or legal entities.

The person preparing the project documentation may be the developer or an individual engaged by the developer or customer on the basis of a contract or entity. The person preparing the project documentation organizes and coordinates the preparation of project documentation and is responsible for the quality of the project documentation and its compliance with the requirements of technical regulations. A person preparing project documentation has the right to carry out certain types of work to prepare project documentation independently, provided that such person meets the requirements for the types of work, and (or) with the involvement of other persons meeting the specified requirements.

Some standards for the design of retaining walls: Code of Practice SP 43.13330.2012 “Structures of industrial enterprises”. Set of rules SP 20.13330.2011 “Loads and impacts”. Set of rules SP 22.13330.2011 “Foundations of buildings and structures.”

Material requirements

The choice of material for a retaining wall and its foundation must be made taking into account many factors and requirements, among which the main ones are: height of the wall, required durability, water resistance, seismic resistance and resistance to chemical aggression, quality of the foundation, availability of local building materials, work conditions, means mechanization and conditions for interface with other structures.

Reinforced concrete thin-element retaining walls are the most economical; compared to massive concrete ones, they require approximately half as much cement with little reinforcement consumption. A significant advantage of reinforced concrete retaining walls is the possibility of using prefabricated structures and erecting them with direct transfer of pressure to soft soils without installing an artificial foundation.

With a height of up to 6 m, cantilever reinforced concrete walls have a smaller volume than ribbed (buttress) walls; for walls with a height of 6 to 8 m, the volumes are approximately the same, and for walls with a height of more than 8 m, the ribbed structure has a smaller volume of reinforced concrete than the cantilever one. Thus, for medium-height and high walls, a reinforced concrete ribbed structure is most appropriate.

Concrete for reinforced concrete retaining walls must be dense, grade from 150 to 600. The reinforcement is steel rods with a diameter of up to 40 mm of a periodic profile of classes A-II and A-III, and for prestressed structures - high-strength wire.

For mounting fittings, as well as for non-design secondary parts of structures, class A-I steel can be used.

For welding of reinforcement bars, electrodes with high-quality coatings of types E42, E42A, E50A and E55 are used in accordance with GOST 9467 - 60.

The use of concrete retaining walls is advisable only when the cost is high and reinforcement is in short supply, since the strength of concrete in massive retaining walls is far from being fully utilized. For this reason, the use of high grades of concrete for them is impractical, however, due to density conditions, concrete of a grade below 150 should not be used. To reduce the volume of masonry, concrete retaining walls can be made with buttresses. For concrete retaining walls of a constant profile, the most economical at a height of more than 150 m will be a profile with a unloading platform at a level of about half the height of the wall from the edge of the foundation. However, profiles with an inclined front edge, inclined towards the backfill, with a protruding front edge, with an inclined base, and even rectangular ones with a height of 1.5 m can also be used. The use of profiles with an inclined rear edge, rectangular and stepped ones can be determined by the requirement of a vertical front edge, for example, for quay walls. However, it must be borne in mind that the strictly vertical front edge of a retaining wall gives the impression of being tilted, so it is usually made with a slight inclination to the vertical (1/20 1/50). The inclined front edge is made with a slope of about 1/3.

Retaining walls made of rubble masonry require less cement consumption compared to concrete ones and can be erected in less time with a simpler organization of work. The use of rubble masonry walls is advisable if there is stone in place.

The rubble masonry must be made of stone of a grade not lower than 150 - 200 on a Portland cement mortar of a grade not lower than 25 - 50, and preferably 100 - 200. In addition to strength, mortars must have plasticity and water-holding capacity. Why is it recommended to introduce plasticizing additives into their composition? For hydraulic walls, rubble stone of a grade of at least 200 is used, and a Portland cement solution of a grade of at least 50 is used.

When choosing a profile for a retaining wall made of rubble masonry, you should be guided by the same considerations as for concrete walls, however, avoiding its complication. Retaining structures with a vertical or inclined front edge and with unloading platforms are used. The back edge is made vertical or very low in height or if there is support at the top of the wall.

If there is torn or small rubble stone on site, then rubble concrete masonry can be used instead of rubble masonry.

Brick walls are allowed up to 3-4 m in height. In this case, it is recommended to use buttresses. Most often, brick walls with a rectangular or stepped profile are used for small underground structures (walls of canals, wells, etc.). For external retaining walls. exposed to atmospheric influences, brickwork undesirable and unsuitable for hydraulic walls. For brick retaining walls, well-burnt brick of grade no lower than 200 is used, with mortar no lower than 25. The use of sand-lime brick is not allowed.

Hard rock stones, high-grade concretes and durable cladding are used when necessary to protect the wall from weathering and from the effects of high water velocities.

For concrete, cladding or the outer layer of masonry, it is allowed to use material that can withstand a hundred times freezing.

If the structure is located in an area where the average monthly temperature of the coldest month is above 5 degrees Celsius. then the material must withstand only fifty times freezing.

When exposed to an aggressive environment, you should use a stone that is resistant to aggression, special cement for concrete and mortar, protective coatings or cladding.

For walls exposed to water, hydraulic concrete should be used (GOST 26633-91 dated 1992.01.01 “Hydraulic concrete”), as well as masonry with cement mortar or waterproofing (cement grout, ironing, shotcrete, asphalt, etc.).

Rib structures can find use for low retaining walls when stone and concrete aggregates are not available on site, as well as for temporary structures.

In seismic areas of high and medium height, retaining walls at the bottom with rocky and dense soils average 1/3 of the height, with medium-density soils ½, with weak soils - 2/3, and with water pressure - up to the full height of the wall. The width of the slab foundation of a thin element retaining wall with an angle profile is usually ½2/3 of the height of the wall. However, these ratios also depend on other factors - on the profile of the retaining wall, its material, etc. Therefore, the given figures should be considered as roughly indicative.

The thickness at the top should be no less than:

for reinforced concrete walls 0.15 m,

for concrete walls 0.14 m,

for rubble and rubble concrete walls 0.75 m,

for brick walls 0.51 m.

For concrete and reinforced concrete walls, the foundation, as a rule, is integral with the wall itself. For brick walls, the foundation is made in the form of an independent structure made of rubble or concrete masonry, protruding beyond the edges of the wall and forming edges with a width of at least 15 cm and no more than the height of the foundation. The foundation projections can be stepped.

Calculation methods

Retaining walls should be calculated according to two groups of limit states:

the first group (on load-bearing capacity) involves performing calculations;

on the stability of the wall position against shear and the strength of the soil foundation;

on the strength of structural elements and joints

the second group (suitability for use) involves checking:

grounds for permissible deformations;

structural elements for permissible crack opening values.

Soil pressure for massive retaining walls (Fig. 2, a). Soil pressure for corner retaining walls should be determined based on the condition of formation of a wedge-shaped symmetrical (and for a short rear console - asymmetrical) collapse prism behind the wall (Fig. 2, b). Soil pressure is assumed to act on an inclined (calculation) plane drawn at an angle e at d = j ў.

The angle of inclination of the calculation plane to the vertical e is determined from condition (1), but is taken to be no more than (45° - j /2)

tg e =(b - t)/h. (1)

The greatest value of active soil pressure in the presence of a uniformly distributed load q on the horizontal surface of the backfill is determined when this load is located within the entire collapse prism, if the load does not have a fixed position.

Calculation of the stability of the wall position against shear

Calculation of the stability of the wall position against shear is made from the condition

Fsa Ј g c Fsr/ g n , (2)

where Fsa is the shear force equal to the sum of the projection of all shear forces onto the horizontal plane; Fsr is the holding force, equal to the sum of the projections of all holding forces onto the horizontal plane; ус - coefficient of working conditions of the foundation soil: for sands, except for dusty ones - 1; for silty sands, as well as silty-clayey soils in a stabilized state - 0.9; for silty-clayey soils in an unstabilized state - 0.85; for rocky, unweathered and slightly weathered soils - 1; weathered - 0.9; highly weathered - 0.8; g n - reliability coefficient for the purpose of the structure, taken equal to 1.2, 1.15 and 1.1, respectively, for buildings and structures of class I, II and III, assigned in accordance with the appendix. 4.

The shear force Fsa is determined by the formula

Fsa = Fsa, g + j sa ,q , (3)

where Fsa, g - shear force from the soil’s own weight is equal to:

Fsa, g = P g h/2 ; (4)

Fsa, q - shear force from the load located on the surface of the collapse prism is equal to:

Fsa,q = Pqyb. (5)

Rice. 2 - Design diagrams of retaining walls: a - massive; b - corner profile

The holding force Fsr for a non-rocky foundation is determined by the formula

Fsr = Fv tg(j I - b) + b c I + E r, (6)

where Fv is the sum of the projections of all forces onto the vertical plane

a) for massive retaining walls

Fv = Fsa tg(e + d) + G с t + g I tgb b 2 /2, (7)

G st is the own weight of the wall and the soil on its ledges.

b) for corner retaining walls (at e Ј q 0)

Fv = Fsa tg(e + j ў) + g ў g f + g I tg b b 2 /2 (8)

where g f is the load reliability factor, taken equal to 1.2; E r - passive soil resistance:

Er = g I l r /2 + cIhr(l r - 1)/tg j I , (9)

where l r is the coefficient of passive soil resistance:

l r =tg2(45° + j I /2), (10)

hr - height of the soil uplift prism

hr =d + btg b (11)

Calculation of the stability of retaining walls against shear should be carried out according to formula (15) for three values ​​of angle b (b = 0, b = j I /2 and b = j I).

With an inclined base of the wall, in addition to the indicated values ​​of angle b, calculations against shear should also be made for negative values ​​of angle b.

When shearing along the base (b = 0), the following restrictions should be taken into account: c I Ј 5 kPa, j I Ј 30°, l r = 1.

The holding force Fsr for a rock foundation is determined by the formula

Fsr =Fvf +Er, (12)

where f is the coefficient of friction of the sole on rocky soil, taken based on the results of direct tests, but not more than 0.65.