Classification of soils by the number of clay particles

Flow Rate Values

Characteristics of clay (non-subsidence) soils by consistency

Design soil resistance

Depth of seasonal soil freezing

Hello everybody!
I plan a 10x10 house with an attached 5x6 aerated concrete garage with brick cladding.
What foundation would be optimal, advise?
Geological surveys were carried out in relation to a part of the cottage village in which my site is located (300 meters away from the last well). Managed to get this info. Here she is:
EGE-1- The soil-vegetative layer is chernozem. Thickness from 0.8 to 1.0 m.
EGE-2– light, sandy, in some places very sandy (to sandy loam), brownish-yellow, from semi-solid to hard-plastic. Sole depth 1.1-1.7. Average thickness 0.4 m.
EGE-3– Sands are fine-grained, light yellow to whitish-gray (in the lower part), quartz, homogeneous, in places with a rare admixture of mica, slightly moist, of medium density, from a low degree of water saturation ( IGE-3a) to water-saturated ( IGE-3b). Up to a depth of 6.0 m, the sole was not opened. The incomplete average thickness is 2.3 m.
EGE-4– Light loam, silty, brownish-yellow, in places with red spots, from hard and soft plastic ( IGE-4a) - in the upper part, to fluid-plastic and fluid ( IGE-4b) - in the lower part, sandy in some areas, with the inclusion of gravel of carbonate rocks. The depth of the sole is 3.0 - 5.5 m. The average thickness is 3.3 m.
EGE-5– Sandy loamy, plastic. They occur in the form of lenses in the central and western parts of the work site (wells 1, 3). Sole depth 5.0m. The average thickness is 0.9m.

Within the area of ​​cottage development, the waters of the Upper Quaternary alluvial aquifer confined to the EGE-4 sands. Level depth ground water varies from 5.8 m - in the western part of the site (well 7) to 2.4 - in the eastern part (well 1). Fluctuations in elevation marks vary from 111.1 to 113.1 m. The bottom of the aquifer is not exposed. In the eastern part of the site, the EGE-4 clay soils act as a local aquiclude, causing local level pressures with an amplitude of up to 0.8–1.7 m (wells 1, 4).
The horizon is fed by atmospheric precipitation and flood waters. The amplitude of seasonal fluctuations in the water level is about 1 m. Semenovsky (HERE, JUST HERE, I HAVE A PLOT!
SOIL PROPERTIES
EGE-2 -The loam is light, sandy, in some places very sandy (to sandy loam), brownish-yellow, from semi-solid to rigid plastic.:
- plasticity numbers - 8.20
- density (in compacted state) – 1.95 g/cm3
- humidity - 15.5%
- fluidity index - 0.41
- density of the skeleton (in compacted state) – 1.69 g/cm3
- coefficient of porosity - 0.55
- degree of humidity - 0.74
According to SNiP 2.02.01-83, in the condition of these soils with a moisture degree of more than 0.8, strength and deformation properties may be characterized by the following:
- deformation modulus, E - 25.0 MPa
- specific adhesion, C - 33.5 kPa
- angle of internal friction - 23.1 degrees.
Loams belong, according to the degree of frosty heaving, to the group of medium heaving.
IGE-3a -
- density (in compacted state) – 1.64 g/cm3
- humidity - 4.14%
- density of the skeleton (in the compacted state) - 1.57 g/cm3
- coefficient of porosity - 0.69
- degree of humidity - 0.16
- the angle of repose in the flooded state - 20 degrees.

- deformation modulus, E - 23.3 MPa
- specific adhesion, C - 0 kPa
- angle of internal friction - 30.4 degrees.

IGE-3b - The sands are fine, low degree of water saturation . According to the results of laboratory studies, it is characterized by standard values:
- density (in compacted state) – 1.97 g/cm3
- humidity - 20.90%
- density of the skeleton (in compacted state) – 1.63 g/cm3
- coefficient of porosity - 0.61
- degree of humidity - 0.90
- the angle of repose in the flooded state - 21 degrees.
According to SNiP 2.02.01-83, strength and deformation properties can be characterized by the following characteristics:
- deformation modulus, E - 20.6 MPa
- specific adhesion, C - 4.2 kPa
- angle of internal friction - 30.9 degrees.
According to the degree of frost heaving, sands belong to the group of practically non-heaving soils.
IGE-4a -. According to the results of laboratory studies, it is characterized by standard values:
- plasticity numbers - 8.49
- density - 1.98 g/cm3
- humidity - 19.13%
- fluidity index - 0.45
- density of the skeleton (in compacted state) – 1.66 g/cm3

- degree of humidity - 0.78
- deformation modulus, E - 3.3 MPa (at р=0.3 MPa)
- specific adhesion (in a water-saturated state), C - 43.3 kPa
- angle of internal friction (in a water-saturated state) - 19.3 degrees.
- relative deformation of subsidence - 0
According to SNiP 2.02.01-83, strength and deformation properties can be characterized by the following characteristics:
- deformation modulus, E - 23.9 MPa
- specific adhesion, C - 32.5 kPa
- angle of internal friction - 22.9 degrees.

IGE-4b - Loams are heavy, silty, hard . According to the results of laboratory studies, it is characterized by standard values:
- plasticity numbers - 9.35
- density (in compacted state) - 1.99 g/cm3
- humidity - 25.32%
- flow rate - 1.30
- density of the skeleton (in compacted state) – 1.55 g/cm3
- porosity coefficient - 0.68
- degree of humidity - 1.08
With a yield index of more than 0.75 according to SNiP 2.02.01-83, the minimum values ​​​​of the indicators of strength and deformation properties of soils can be conventionally accepted:
- deformation modulus, E - 5 MPa
- specific adhesion, C - 12 kPa
- angle of internal friction - 12 degrees.
Loams are non-sagging and belong to non-swelling soils. According to the degree of frosty heaving, loams are classified as medium-heaving.
IGE-5 - Sandy loamy, hard to plastic . According to the results of laboratory studies, it is characterized by standard values:
- plasticity numbers - 5.02
- density (in compacted state) – 2.63 g/cm3
- humidity - 14.26%
- fluidity index - 0.52
- density of the skeleton (in the compacted state) - 1.78 g/cm3
- specific adhesion (in a water-saturated state), C - 11.3 kPa
- deformation modulus, E - 6.7 MPa (at р=0.3 MPa)
- coefficient of porosity - 0.48
- degree of humidity - 0.78
According to SNiP 2.02.01-83, strength and deformation properties can be characterized by the following characteristics:
- deformation modulus, E - 30.2 MPa
- specific adhesion, C - 17.7 kPa
- angle of internal friction - 27.9 degrees.
Sandy loams are non-sagging and belong to non-swelling soils. According to the degree of frosty heaving, sandy loams are classified as strongly heaving.

MINISTRY OF ROADS OF THE RSFSR

STATE ROAD DESIGN AND SURVEY AND SCIENTIFIC RESEARCH INSTITUTE
HYPRODORNIA

REFERENCE
REPORT ON ENGINEERING AND GEOLOGICAL SURVEYS
WHEN DESIGNING ROADS
AND BRIDGES

Approved at the meeting of the STC section

Giprodornia of the design part

Minutes No. 10 dated 12/23/86

MOSCOW 1987

Standard report on engineering and geological surveys in the design of roads and bridges / Giprodornia. - M.: TsBNTI of the Minavtodor of the RSFSR. 1987.

The main task of issuing the Etalon is to unify the forms of field, laboratory and cameral documentation of engineering and geological work.

The standard report provides for all the main types of notes, drawings, statements and charts issued by the Geological Survey of Giprodornia. When compiling the Standard, the requirements of the current state standards were taken into account, normative documents and allowances for them.

Ch. geologist - engineer R.T. Vlasyuk (technical department of Giprodornia) in the development of previously published (in 1985) samples of engineering-geological passports for surveying roads.

Director of the Institute

cand. tech. naukE.K. Kuptsov

1. GENERAL PROVISIONS

The technical report on engineering and geological surveys must contain all the data necessary for the development of design estimates corresponding to the design stage of highways.

Reports on detailed engineering-geological surveys (for drawing up a project and a working draft) should consist of an explanatory note, the text of which is illustrated by drawings and photographs, graphic applications, statements, engineering-geological passports of bridge crossings, overpasses, places for individual design of subgrades, sites for buildings and structures, deposits of soil and road construction materials.

Instructions on the preparation and composition of engineering-geological passports are given in the samples of engineering-geological passports for surveying roads and structures on them, published by the technical department of Giprodornia in 1985.

This Standard provides general guidance on the scope of a survey report. In each individual case, it is determined individually depending on local conditions, this especially applies to surveys of bridge crossings.

Sample cover page of the report

MINISTRY OF ROADS OF THE RSFSR
HYPRODORNIA
(Branch)

REPORT
ON ENGINEERING AND GEOLOGICAL WORKS FOR
DRAFTING A PROJECT (WORKING DRAFT)
FOR CONSTRUCTION (RECONSTRUCTION)
ROAD (BRIDGE CROSSING
THROUGH R. …………………..)………………………………….

Head of departmentI.O. Surname

Chief geologist (specialist) of the departmentI.O. Surname

Chief (senior) geologist

expeditions (parties)I.O. Surname

19 ... g.

2. SCHEME OF EXPLANATORY NOTE

2.1. Introduction

Administrative and geographical boundaries of the survey area.

On whose orders the work was carried out.

Work production time.

The degree of exploration of the territory of the object of research.

Organization of field work (number of parties, detachments).

Producers of works (chief geologist, head of the party, senior engineer, etc.). Position, surname of the author of the report.

Technology for the production of engineering and geological works (driving pits and boreholes, type and brand of machines, geophysical methods of exploration, field methods for studying soils).

The completeness and quality of the work performed.

2.2. Natural conditions of the area, works

2.2.1. Climate:

General climatic characteristics of the region with indication of climatic zones by sections of the route;

Precipitation, their distribution by months, showers, average long-term and maximum thickness of snow cover, number of days with snowfall, duration of the period of snow blizzards and number of days with blizzards, duration of the winter period;

Information from the road maintenance service about snow drifts on the roads in the area of ​​the route;

The number of days with thaws, ice, fogs;

Average, maximum and minimum air temperatures, transition of average daily temperatures through 0 and 5 degrees; depth of soil freezing, absolute and relative air humidity, dates of freezing and opening of rivers, information about snow avalanches and mudflows for mountainous areas;

Wind; prevailing winds according to the seasons, winds with a speed of over 4 m/s. Winter wind rose, and in the southern arid regions - summer.

2.2.2. Relief and hydrography:

General geomorphological characteristics of the route area highway;

Regionalization of the route according to the relief;

Security of natural water runoff, waterlogging;

Hydrographic network of the route area;

List of medium and large bridge crossings.

2.2.3. Soils and vegetation:

General characteristics of the soils of the region as a whole and by plots;

Description of the main soil types along the highway route;

Vegetation cover of the area of ​​the highway route;

Possibility of using vegetation for road construction.

2.2.4. Geology, tectonics and hydrogeology:

Feature of the tectonics of the area, seismicity;

Brief description of the geological structure of the area of ​​the road route in general and in individual sections;

Characteristics and depth of occurrence of bedrocks;

Characteristics of rocks of the Quaternary age;

Surface runoff conditions, perched water formation;

Groundwater, distribution and features of their occurrence;

Estimated level of the groundwater horizon and methods for its determination during the engineering-geological survey;

Chemical composition of ground and surface waters (aggressive properties in relation to concrete, suitability for mixing concrete, suitability for drinking);

Sources of water for technical purposes (watering when laying the subgrade).

2.3.1. Soils:

General characteristics of soils of engineering-geological elements along the entire length of the route and in sections;

Granulometric composition and physical properties of the main soil varieties ( natural humidity, optimal moisture content and density, determined on the Soyuzdornia standard compaction device, plasticity limits) soil categories according to the difficulty of development;

Soil evaluation as building material for the construction of subgrade and as the foundation of road structures;

Chemical composition (content of water-soluble salts in the area of ​​development of saline soils) according to local agricultural enterprises and according to our own laboratory research.

2.3.2. Modern physical and geological processes:

The presence and intensity of the manifestation of modern physical and geological processes, their impact on the operation and stability of road structures;

The presence of landslides, talus, karst, swamps, wet excavations and other places that require individual design of the subgrade.

2. 3 .3. Engineering and geological conditions of construction:

Features of the construction of sections of standard and individual design of the subgrade;

Features of the construction of artificial structures and objects of the ASG.

Note. if necessary, it can be compiled along the route of the highway and road structures as a whole or separately along the subgrade, small artificial structures, bridge crossings and overpasses and facilities of the CBC.

2.4. Road building materials

The literary and archival sources used are survey data from previous years, as well as data for resolving the issue of providing the facility with building materials.

Assessment of the geological structure of the considered area of ​​the road laying in terms of the possibility and conditions for obtaining road construction materials.

A brief general description of surveyed and explored deposits of road building materials by groups of stone, gravel, sand. Grades and classes of materials according to SNiP.

Near-road deposits of soils for backfilling embankments. Their location, conditions of development and transportation.

Availability of operating quarries and bases for the processing of road construction materials. The quality of materials, the conditions for their receipt and delivery.

Availability of local industries producing waste suitable for use as materials for road construction. Terms of receipt and delivery of waste. The quality of waste as road building materials.

Analysis of the provision of construction with local and imported road building materials and their qualitative characteristics.

2.5. Results of survey of existing highways

2.5.1. Ground bed:

Characteristics of the subgrade in general and in characteristic areas;

Deformation, damage and destruction of the subgrade;

The degree of compaction of the subgrade;

The condition of the drainage system;

2.5.2. Road clothes:

Condition of pavement in general and in specific areas;

Availability and thickness of structural layers of pavement;

Composition and characteristics of structural layers of pavement;

2.6. conclusions

The main results of engineering-geological studies of the highway route and road structures.

Notes.

1. The text of the note is illustrated with photographs of production processes, types of terrain, characteristic outcrops, individual difficult places, crossings over watercourses, individual sections showing the condition of existing roads, etc.

2. The climate of an area can be represented by graphs of climate data, curves of temperature, precipitation and wind roses.

For arid regions, not only the winter wind rose should be applied, but also the summer one.

3. When submitting a report to the geological fund, its composition and execution must meet the requirements for reporting materials submitted to the geological fund of the USSR Ministry of Geology and the Mosoblgeofond.

Clay soils are often referred to as good, durable soils, as a result of which the question arises of how to save on foundations if clays occur on the construction site. In fact, good, firm clay close to the surface is rare, in contrast to the widespread sandy loam and loam. How to understand what kind of soil is on the site, and what kind of foundation is better on clay soil, we will talk in this article.

Types and types of clay soils. Main characteristics

Clay soils are classified as cohesive soils, sandy soils are non-cohesive. Cohesion is the ability of a soil to hold together when both wet and dry. Depending on the granulometric composition, cohesive soils are divided into:

1. Clay. The fraction is not larger than 0.01 mm with a percentage by weight of at least 50%.
2. Loams. The fraction is not larger than 0.01 mm with a percentage of 30-50% and the presence of a fraction larger than 0.01 mm up to 70%.
3. Sandy loam. The fraction is not larger than 0.01m with a percentage of less than 30%.
4. Loessy. Fraction 0.002-0.05 mm, content of clay particles 5-30% with porosity 40-55%.

For the construction of the foundation, clay is best, loess is the worst. Moreover, these soils are not always in a "clean" state. For example, loess-like loams are widespread.

An extremely important parameter that greatly affects the bearing capacity of cohesive soils is the consistency index. It depends on water saturation and is measured in fractions of a unit. The lower the value, the harder (drier) the ground.

The choice of the type of foundation largely depends on the consistency of the clay soil.

It is easy to recognize the type of clay soil based on its main characteristic- connections. It is necessary to moisten the soil to a state closest to plasticine. If, when you try to roll out the tourniquet (“sausage”) with your fingers, the ends do not sprinkle, it is clay or loam. These two soils are similar, there is no need to distinguish between them. The remaining two (sandy loam and loess) are also easy to distinguish from each other. If a sample with an undisturbed structure in a dry state easily crumbles with fingers, this is sandy loam. Loesses are fastened with easily water-soluble salts and in a dry state have strength, characterized by the expression "a shovel does not take."

Foundation selection for hard and semi-hard clay soils.

Solid and semi-solid loams and clays are an excellent building base. It is stable and durable. Allows you to perform all types of earthworks. On these soils, it is advisable to use columnar foundations for frame structures and strip foundations for wall structures. For private construction, the use of foundation slabs or piles is doubtful.

The choice of foundation for hard-plastic and soft-plastic clay soils.

For this type of soil, all types of foundations are used, from tapes and slabs to piles. For soft-plastic consistency, the use of free-standing columnar foundations. In private construction, preference should be given strip foundations of sufficient width, insulated shallow-depth slabs, screw or bored piles of small length.

The choice of foundation for fluid-plastic clay soils.

Cohesive soils of plastic and especially fluid-plastic consistency impose a number of restrictions on the work. The slopes of the pits (trenches) are not stable, they are prone to "sagging". The device of this type of foundation is very difficult, as bored piles. After drilling wells, they quickly “silt up”, the walls settle. On such soils, it is advisable to use insulated shallow foundations (for example, insulated swedish stove), bored piles in casing pipes, bored injection and screw piles. The latter are widely used in private construction due to their low cost and ease of installation.

Another dangerous property of water-saturated cohesive soils is frost heaving. It most often manifests itself in finely dispersed (cohesive) soils with a sufficient amount of water. Thus, soft and fluid-plastic clay and loamy soils are especially often subject to the forces of frost heaving. Measures to counteract this factor are divided into two categories: deepening the foundation at least the freezing depth (depending on the climatic region of construction) and warming the basement of the building (including the blind area).

The choice of foundation for loess-like soils.

The most dangerous types of cohesive soils are loess and loess-like loams. It is a highly porous soil with a high bearing capacity when dry. But when water gets in, it soaks very quickly, turns into “porridge”, loses its bearing capacity and becomes self-compacting. The last property is called subsidence. Loess-like soils are divided into the 1st and 2nd type according to subsidence. The first one gives independent shrinkage under its own weight when soaking by a value of not more than 5 cm per meter of soil thickness, the second - more than 5 cm.

For subsiding soils, it is recommended to use broadened shallow foundations (wide foundation strips, solid slabs with reinforced monolithic basement parts of the walls) as well as piles passing through the subsidence and driven into solid soils.

Important measures in the presence of subsidence include the installation of a waterproof blind area with a width of at least 1.5 m for the 1st and 2.0 m for the 2nd type of subsidence. Water-bearing communications in places of underground laying, as well as passing through basement must be enclosed in waterproof sleeves or trays.

The characteristics of the soil determine not only the design of the foundation-basement part, but also the ability to build a house in general. It is known how problematic it is to build something, pile it on quicksand, on peat bogs, where a deceitful substrate is hidden under the surface layer of clay-like sediments.

During construction, stage 1 of the work is to determine the characteristics of the soil. And also to find out the water content of the site, the depth of freezing, the likelihood of frost heaving, and as a result, choose the most optimal foundation design.

To create an underground part of the house according to the principle of "with a margin of safety" is a great loss to the financial and economic situation. After all, a 2-3-fold increase in heavy filling materials may “seem” normal.

The correct direction of overcoming production complications is research and study of the soil, determination of characteristics. But is it possible to do this "by eye" with your own hands?

What's in the pit

Even a person far from geology will be able to distinguish sand from sandy shale - a very hard rock. These are obvious clear differences.

But difficulties arise when it is necessary to determine the varieties of clay soils.

What is in the pit - clay, loam or sandy loam? And what is the percentage of pure clay in such soils?

The presence of clay and dust-like particles determines the tendency of soils to heaving.

Next, we consider the possibility of independently determining the types of clay soils. You can use GOST 25100-95 “Soils. Classification". Everything is painted there from A to Z. But the practical benefit is still not great. Since, for example, the parameter "tensile strength" cannot be measured without a laboratory.

But first, create a sufficient depth of the pit to take the soil lying both opposite the walls of the foundation, which is very important (lifting forces directed tangentially to the walls), and under the sole

Plasticity is an important characteristic

The most important characteristic of clay soils is the "number of plasticity". It characterizes the ability of soils to hold water. The plasticity number for clay soils has the following values:

• Sandy loam - 1 - 7
• Loam - 7 - 17
• Clay - >17

The more plastic material, the more water in it, and it is better molded - sticks together, retains its shape integrity even in the form of thin figures.

But the plasticity number is the result of laboratory research.

Let's try to determine the type of soil in the foundation pit without resorting to a finite plasticity number, but using visual differences.

What to do to determine the qualities

1. We rub a piece of soil in our hands, try to determine by touch - if there are sand particles in it. Based on our feelings, we conclude:

• when grinding, sand is not felt - it is clay;
• when rubbing, sand is felt, although the soil looks like clay - it is loam;
• the soil is rubbed into sand and dusty particles - this is sandy loam.

2. With palms, we roll a lace and other figures out of the ground:

• clay - the cord rolls easily, and it is very thin. After that, we make a ball out of the cord, flatten it - the edges of the ball did not crack during deformation;
• loam - the cord rolls, but the edges of the ball cracked when it was squeezed;
• sandy loam - the cord rolls with great difficulty, or does not roll at all.

More ways to determine soil

For those who want to replace geological studies with their own hands, there is a table - Methods for determining the soil - here it is necessary to roll a thin cord, a ball out of the soil, determine the plasticity and inclusion of particles by touch, look at the composition with a magnifying glass ...

With each sample taken from a certain depth of the pit, several manipulations must be done according to the data in the following table.

The described, not scientific, but practical method, is still very rude. The percentage of sand particles in the soil cannot be obtained by such methods.

The division of soils according to the number of plasticity and the percentage of sand particles is given in the table.

More information on the definition of qualities.

The method of separating sand from clay for studying the soil

You can manually separate sand from clay in a jar of water. And then measure the thickness of their layers with a ruler, which, in a rough approximation, will indicate the approximate percentage of clay from sand. You can fill your hand in such experiments if you repeat them many times, taking samples of obviously different soils.

The following is done. A jar of water is taken, soil is poured there and diligently chattered. After complete stirring, it is necessary to allow some time for the suspension to settle, sometimes for small particles it takes a very long time. Sand settles, forms a visible compacted layer below, and clay particles are buoyant, remain in the thickness or rise up.

By measuring the thickness of the visible layers at the top and bottom of the glass container, one can roughly judge the nature of the soil. Correlate these data with the above table values, and therefore give the soil its name and characteristics without waiting for laboratory analyzes.