Every soil consists of individual particles, and the less these elements are connected to each other, the easier the soil is to develop.

All soils can be roughly divided into the following 5 groups according to the degree of their cohesion:

Characteristics of the most important soils

I. Loose, granular soils

- resulted from the destruction of rocky soils by wind and water.

Granular soils include:

— Sand. The sand particles are not connected to each other. Clean, dry sand spreads when sprinkled in a heap.

Sands, depending on their origin, can be mountain, ravine, river or sea. Mountain and ravine sands consist of individual, uneven grains of sand with sharp edges. River and sea sands have rounded, smooth grains of sand.

Based on the size of individual grains, they are distinguished:

— fine sand – grains up to 0.5 mm in size predominate;

– medium sand – grains from 0.5 to 1 mm predominate;

— coarse sand – grains from 1 to 3 mm predominate;

Gravel- This is a mixture of rounded pebbles with dimensions in diameter from 3 to 40 mm, not interconnected.

Coarse gravel, consisting of pebbles from 40 to 120 mm in diameter, is called pebbles.

Also applies to loose and loose soils sandy loam, consisting of sand with an admixture of clay in the amount of 3-10% of the total volume.

II. Plant soils

Plant soils include all surface soils containing the remains of rotten plants (humus), for example black soil and peat. Plant soils are easily loosened and washed away by water, easily absorb water and, when saturated with water, spread out, turning into mud.

III. Dense and viscous soils.

Dense, viscous soils include clays and loams. Clay- This is soil consisting of very small particles tightly bound together.

According to the degree of density, clay is divided into heavy (dense) and light clay.

The main property of clay is that when saturated with water, it swells greatly and increases significantly in volume. Along with this, clay is an almost waterproof soil, since water almost does not pass through the clay.

When dry and under pressure, clay shrinks (settles). As the humidity in the clay decreases, the adhesion of the particles among themselves increases, and it gradually turns into a solid mass that is difficult to work with tools.

Clays mixed with sand are called loams. There are light loams - soil containing 10-20% clay, and heavy loams containing 20-30% clay.

IV. Hard, rocky soils

Hard and rocky soils can be of different types. Usually distinguished:

• soft and layered rock, mined with a pick, crowbar, wedges;
• hard (dense) rock, mined only with the help of explosives.

V. Liquefied soils

Liquefied soils include the so-called quicksand. Quicksand is sandy-clayey or silty-sandy soil, consisting of very small particles and usually highly saturated with water. The quicksand spreads and does not stay on the slope.

Soil classification

It is customary to divide soils according to the degree of difficulty of their development into 7 categories indicated in the table below:

Category soil	Soil name	Weight 1 cu. m of soil in a dense body	Development method and tool	Difficulty level of soil development
	Sands		Developed with picking shovels and spades
	Supeski
	Vegetable soil
	Chernozem
	Peat without roots
	Light loess-like loams		Mined with shovels with minor picking
	Gravel fine and medium up to 15 mm
	Dense plant soil
	Peat and plant soil with roots
	Sand and vegetable soil with crushed stone
	Bulk compacted soil with crushed stone
	Sandy loam mixed with crushed stone
	Oily clay		Developed with spades with continuous pick
	Heavy loams
	Coarse gravel and pebbles with grain sizes from 15 to 40 mm and crushed stone
	Plant soil or peat with tree roots
	Heavy break clay		Developed with a spade using continuous picks, crowbar or wedge and hammer
	Oily clay and heavy loam with an admixture of crushed stone, pebbles, construction waste and cobblestones weighing up to 10 kg
	Large pebbles up to 90 cm in size, pure or mixed with cobblestones weighing up to 10 kg
	Rocky soils (soft)		Developed partially by hand using percussion instruments and explosions
	Rocky soils (dense)		Are developed by explosions
	Quicksand		Works with shovels, buckets and scoops

The degree of difficulty of development shows that if in category I soil there is 1 cubic meter for development. m of soil takes time equal to one, then in soil, for example, category IV to develop 1 cubic meter. m of soil will take 2 times longer.

In winter, due to soil freezing, the difficulty of developing most soils increases greatly. This happens because the water in the soil strongly binds its particles when it freezes. For winter work there is a special classification of soils, shown in the table below.

The difficulty of mining rocky soils does not depend on the time of year, and quicksand in winter is usually even easier to mine than in summer.

The depth of freezing depends on a number of conditions. The less snow, the longer the winter, the more frost, the deeper the soil freezes.

The deeper the soil freezes, the more difficult it is to develop it.

Group I Soils that require loosening using a pick and partial crowbar		Group II Soils that require the use of a crowbar and partially a wedge with a hammer to loosen them
	At freezing depth in m	Soil category	At freezing depth in m
	Up to 0.75	I.	More than 0.75
		II.
		III. (except for heavy loam and oily pure clay)	0,75
		IV. (quicksand)

III group Soils that cannot be mined with a crowbar and require the use of a wedge and hammer or blasting		IV group Soils that are not amenable to or extremely difficult to develop with a wedge and hammer and require the use of blasting operations
	At freezing depth in m	Soil category	At freezing depth in m
	More than 0.75
III (except for loam and pure fatty clay)
IV (quicksand)	More than 0.75	IV, as well as heavy loam and pure oily clay	Regardless of freezing depth

We give the highest value of soil freezing for some areas of Russia and Ukraine:

• Moscow - 1.6 m
• Chelyabinsk - 2.4 m
• Odessa - 0.8 m
• Kyiv — 1.0

The data is as close to real as possible. The source is technical materials from technical schools approved by GUUZ.

Basic properties of soils

The main properties of soils: volumetric weight, the ability of the soil to hold a slope and loosening ability.

Volumetric weight is 1 cubic meter of soil in a dense body and in a state of natural moisture, i.e. in the condition in which the soil is in the ground. The volumetric weight of the most important soils is indicated in the first table of this article.

If you take dry soil and freely pour it in a heap on a horizontal surface, then its particles will form some slopes. In this case, the soil is said to have a natural slope. The angle at which such a slope is located in relation to the horizontal surface is called the angle of repose and is measured in degrees.

The magnitude of these angles depends on the degree of soil moisture. The stronger the bond between individual soil particles, the steeper the slope the soil can maintain. Some soils can support a vertical slope (rock, dry loam, etc.), while others crumble, forming a gentle slope (sand, gravel, sandy loam).

The table below shows the values ​​of the angles of repose for various soils:

Name of soil	Angle of repose in degrees
	Dry soil	Wet soil	Wet ground
Gravel
Coarse sand
Sand medium
Fine sand
Loam
Vegetable soil
Peat without roots	40	25

The soil taken out of the ground is loosened, i.e. its volume increases because more voids are formed in the loosened soil than it was before when it was in a dense state (in a dense body).

I distinguish between initial and residual loosening of the soil. If the soil has just been thrown out of the excavation, it is initially loosened.

Over time, this discarded soil becomes compacted, but it never reaches the density it had before mining. A slight increase in its volume (loosening coefficient) will still remain. This loosening remaining after final compaction of the soil is called residual loosening.

Both initial and residual loosening are measured as a percentage increase in the volume of soil relative to its volume in a dense body (before development).

The table below shows the percentage of initial and residual loosening for various soils.

Initial and residual loosening of soils

For example. It is necessary to calculate how much the volume of 100 cubic meters has increased. m of clay when loosening it. According to the table, we find that the percentage of the initial increase in volume will be from 24 to 30. Let us take it on average to be 27%. The percentage of residual loosening is approximately 4-7, or an average of 6%. Then the initial volume of clay thrown out of the pit will be equal to: 100+100*27/100 = 127 cubic meters. The residual volume after the final compaction of the poured soil will be: 100+100*6/100= 106 cubic meters of soil.

General information and classification of soils

G runts - these are any rocks (sedimentary, igneous, metamorphic) and solid industrial waste lying on the surface , the earth's crust and included in the sphereimpact onthem a person atconstruction of buildings, structures, roads and other objects.

When assessing the properties of soils acting as foundations, much attention is paid to their deformation and strength indicators. The indicators are largely dependent on many other characteristics of soils: chemical and mineral composition, structures and textures, the nature of the interaction of soils with water, the degree of their weathering and a number of others. Underestimation of certain features of the properties of “foundation soils” entails errors in the design and construction of buildings and structures, which ultimately leads to a loss of soil strength during operation.

Prediction of changes in the properties of pounds over time under the influence of various influences is possible only if we have complete information about how they were formed during the process of genesis and their entire subsequent “life.”

Soil condition

Recently, specialists in engineering geology have paid much attention to such an important category of soil assessment as their state. We have already discussed the concept of “soil condition” above; here we will try to somewhat streamline the previously presented information. It should be noted that there is no clearly defined definition of this category yet. The characteristics that determine the condition of pounds include degree of fracturing, weathering,humidity, water saturation, density etc. Characteristics such as cracking and weathering, determine the properties of rocks in the sample and in the massif; As is known, such a value as the compressive strength in a sample significantly exceeds its value in the massif, sometimes up to two orders of magnitude. The degree of weathering has a slightly different influence on the formation of soil properties in the sample and in the massif. Weathering cracks are usually filled with secondary mineral material, and this, naturally, sharply increases the heterogeneity of the massif, thereby reducing or, more precisely, changing the strength, deformation and filtration properties of the rocks in the massif.

Humidity level most often taken into account when assessing the properties of dispersed soils. It determines the occurrence, “revival” and development of such unfavorable phenomena and processes as landslides, solifluction, and in some cases contributes to mudflow formation and a number of other phenomena. The degree of humidity affects the deformation-strength characteristics of soil masses and the consolidation of soils at the base of structures when loads of engineering structures are applied to them. Very close to the humidity level degree of water saturation, which is currently more applicable to rocky, fractured soils. These two categories determine the ability of soils to deform under load and consolidate; significantly affect the strength characteristics of soil masses; in climatic zones subject to sharp temperature fluctuations, in areas where frozen soils are widespread, the degree of humidity and the degree of water saturation significantly influence the frost resistance of rocks in the massif.

For dispersed soils, the degree of their raftness For example, there are under-consolidated silty and sandy soils, such as fine-grained aeolian soils common in the southern part of the Kara-Kum, aeolian-marine (dune) sands of the Baltic coast, and loess soils of various origins.

The under-compacted state of these soils is one of the reasons for subsidence phenomena, partly liquefaction of sands, heterogeneous deformations at the base of structures, and disturbances in the stability of rocks in the slopes of natural and artificial excavations.

All of the listed characteristics of the state of soils in their “limiting” values ​​sharply worsen the properties of massifs when vibration, dynamic, in particular, seismic loads are applied. Heavily cracked, weathered, water-saturated or wet, under-compacted soils in the massif significantly reduce the possibility of using them as the foundation of critical structures. When calculating the seismic stability of structures designed on soils that are in the above states, according to current regulatory documents, it is required to increase the design values ​​taking into account seismic impacts, in some cases by 1 point higher than the general seismic intensity established for the entire area.

Soil classification

Soil classification can be general, partial, regional and sectoral.

Task general classifications - if possible, cover all the most common types of rocks and characterize them as soils. Such classifications should be based exclusively on a genetic approach, in which it is possible to connect the engineering-geological properties of rocks with their genetic characteristics and trace changes in these properties from one group of soils to another. These classifications serve as the basis for the development of all other types of classifications.

Private classifications subdivide and subdivide soils in detail into separate groups according to one or more characteristics. These classifications include the following classifications:

Sedimentary, clastic, sandy-clayey soils by granulometric composition,

Clay rocks - according to the number of plasticity,

Loess rocks - according to the degree of subsidence, etc.

These classifications may be developments or components of general classifications.

Regional classifications consider soils in relation to a certain territory. They are based on the age and genetic division of breeds found in a given territory. The division of groups of pounds is carried out based on the formation-facies theory of rocks.

Industry Pound classifications are made in relation to the demands of a particular type of construction. Naturally, such classifications are based on the provisions of the classifications described above and are, as it were, a concrete result of general classifications for resolving issues in the engineering-geological assessment of territories and construction sites.

The classification of pounds reflects their properties. Currently, according to GOST 25100-95, pounds are divided into the following classes - natural: rock, dispersed, frozen and man-made formations. Each class has its own divisions. Thus, pounds of rock, dispersed and frozen classes are combined into groups, subgroups, types, types and varieties, and technogenic pounds are first divided into two subclasses, and then also into groups, subgroups, types, types and varieties. The classification of pounds according to GOST 25100-95 is shown in abbreviated form in the table:

Construction classification of soils

Classes	Groups	Subgroups	Types	Kinds	Varieties
Rocky soils (with rigid structural connections)	Rocky soils	Igneous rocks Metamorphic rocks Sedimentary	Silicate Silicate Carbonate Ferrous Silicate Carbonate	Granites, basalts, gabbro Gneisses, schists Marbles, etc. Iron ores Sandstones, conglomerates Limestones, dolomites	Are distinguished by: Strength Densities weathered Water solubility Softening in water 6. water permeability, etc.
	Semi-rocky soils	Magmat. Extrusive rocks Sedimentary	Silicate Silicate Siliceous Carbonate Sulfate Halide	Volcanic tuffs Mudstones, siltstones Opoki, tripoli Diatomites Chalk marls Gypsum, anhydrite Galita and others.
Dispersed soils (with mechanical and water-colloidal bonds)	Cohesive soils Non-cohesive soils	Sedimentary rocks Sedimentary rocks	Mineral Organomineral Organic Silicate, carbonate, polymineral	Clay soils Silts, sapropels, peat lands sands, coarse soils	Are distinguished by: Granulometric and mineralogical composition Plasticity number Swelling Subsidence Water saturation Porosity coefficient Densities, etc.
Frozen soils (with cryogenic structural bonds)	Rocky soils Semi-rocky soils Cohesive soils Icy soils	Frozen igneous, metamorphic and sedimentary rocks Frozen igneous volcanic rocks Sedimentary rocks Frozen Sedimentary Rocks In-ground buried	Ice mineral Ice mineral Ice organomineral Ice organic	All types of igneous, metamorphic and sedimentary soils All types of dispersed cohesive and non-cohesive soils Glacial Ice, river, lake, etc.	Are distinguished by: Ice content Temperature-strength properties Salinity Cryogenic texture, etc.

Rocky soils. Their structures have rigid crystalline bonds, for example, granite, limestone. The class includes two groups of soils: 1) rocky, which includes three subgroups of rocks: igneous, metamorphic, sedimentary cemented and chemogenic; 2) semi-rocky in the form of two subgroups - igneous outpouring and sedimentary rocks such as marl and gypsum. The division of soils of this class into types is based on features of the mineral composition, for example, silicate type - gneisses, granites, carbonate type - marble, chemogenic limestones. Further division of soils into varieties is carried out according to properties: according to strength - granite is very strong, volcanic tuff is less strong; In terms of solubility in water, quartzite is very water-resistant, limestone is not water-resistant.

Dispersed soils. This class includes only sedimentary rocks. The class is divided into two groups - cohesive and non-cohesive soils. These pounds are characterized by mechanical and water-colloidal structural bonds. Cohesive pounds are divided into three types - mineral (clay formations), organo-mineral (silts, sapropels, etc.) and organic (peat). Non-cohesive pounds are represented by sands and coarse rocks (gravel, crushed stone, etc.). Pound varieties are based on density, salinity, particle size distribution and other indicators

Frozen soils. All soils have cryogenic structural bonds, i.e. the cement of the soil is ice. The class includes almost all rocky, semi-rocky and cohesive soils located in conditions of negative temperatures. To these three groups is added a group of icy soils in the form of above-ground and underground ice. The types of frozen soils are based on icy (cryogenic) structures, salinity, temperature and strength properties, etc.

Technogenic soils. These soils represent, on the one hand, natural rocks - rocky, dispersed, frozen, which for some purpose were subjected to physical or physico-chemical influence, and on the other hand, artificial mineral and organomineral formations formed in the process of domestic and human production activity. The latter are often called anthropogenic formation. Unlike other classes, this class is first divided into three subclasses, and after that each subclass, in turn, is divided into groups, subgroups, types, types and varieties of soils. Varieties of technogenic soils are distinguished on the basis of specific properties.

The purpose of geotechnical work during construction is to determine the characteristics and properties of the soils used for the foundation of the future building or structure. To simplify these works, a construction soil classification. What are the main types of soils and their construction properties?

Construction classification of soils and types of soils

Soils are varied in their composition, structure and nature of occurrence. Construction classification of soils and types of soils are determined in accordance with SNiP II-15-74 part 2.

Soils are divided into two classes: rocky- soils with rigid (crystallization or cementation) structural connections and non-rocky- soils without rigid structural connections.

1. Rocky soils

Rocky– soils with rigid structural connections occur in the form of a continuous massif or in the form of a cracked layer. These include igneous (granites, diorites, etc.), metamorphic (gneisses, quartzites, schists, etc.), cemented sedimentary (sandstones, conglomerates, etc.) and artificial.

They are waterproof, incompressible, have significant compressive strength and do not freeze, and in the absence of cracks and voids they are the most durable and reliable foundations. Fractured layers of rocky soils are less durable.

Rocky soils are divided according to their tensile strength, solubility, softness and salinity.

2. Non-rocky soils

Non-rocky soils are sedimentary rocks without rigid structural connections. Based on particle size and content, they are divided into coarse-clastic, sandy, silty-clayey, biogenic And soil. A characteristic feature of these soils is their fragmentation and dispersion, which distinguishes them from very durable rocks.

2.1. Coarse soils

Coarse clastic – loose fragments of rocks with a predominance of fragments larger than 2 mm (over 50%). Based on their granulometric composition, coarse soils are divided into: boulder d>200 mm (with a predominance of unrounded particles – blocky), pebble d>10 mm (with unrounded edges – crushed) And gravel d>2 mm (with unrounded edges – woody). These include gravel, crushed stone, pebbles, and debris.

These soils are a good foundation if there is a dense layer underneath them. They shrink slightly and are reliable foundations.

If there is more than 40% sandy aggregate or more than 30% silty-clayey aggregate of the total mass, only the fine component of the soil is taken into account, since it is this that will determine the bearing capacity.

Coarse soil can be heaving if the fine component is silty sand or clay.

2.2. Sandy soils

Sandy– consist of particles of quartz grains and other minerals with a particle size of 0.1 to 2 mm, containing clay no more than 3% and do not have the property of plasticity. Sands are divided according to grain composition and the size of the predominant fractions into gravel lines d>2 mm, large d>0.5 mm, medium size d>0.25 mm, small d>0.1 mm and dusty d=0.05 - 0.005 mm.

Soil particles with a particle size of d=0.05 - 0.005 mm are called dusty. If the sand contains from 15 to 50% such particles, then they are classified as dusty. When there are more dust particles in the soil than sand particles, the soil is called dusty.

The larger and purer the sand, the greater the load the base layer can withstand. The compressibility of dense sand is low, but the rate of compaction under load is significant, so settlement of structures on such foundations quickly stops. Sands do not have the property of plasticity.

gravelly, large And medium size Sands become significantly compacted under load and freeze slightly.

The type of coarse-grained and sandy soils is determined by the granulometric composition, the variety - by the degree of moisture.

2.3. Silty-clayey soils

Silty-clayey soils contain dusty (0.05 - 0.005 mm in size) and clay (less than 0.005 mm in size) particles. Among silty clay soils, there are soils that exhibit specific unfavorable properties when soaked: subsidence And swelling. TO subsidence include soils that, under the influence of external factors and their own weight when soaked with water, give a significant sediment, called drawdown. Swelling soils They increase in volume when moistened and decrease in volume when dry.

2.3.1. Clay soils

Clayey– cohesive soils, consisting of particles with a particle size of less than 0.005 mm, having a mainly scaly shape, with a small admixture of small sand particles. Unlike sands, clays have thin capillaries and a large specific contact surface between particles. Since the pores of clay soils are in most cases filled with water, when the clay freezes, it heaves.

Clay soils are divided depending on the plasticity number into clay(with clay particles content more than 30%), loams(10...30%) and sandy loam(3...10%).

The bearing capacity of clayey foundations depends on humidity, which determines the consistency of clayey soils. Dry clay can withstand quite a lot of load.

The type of clay soil depends on the plasticity number, the variety - on the fluidity index.

2.3.2. Loess and loess-like soils

Loess and loess-like – clayey soils containing a large amount of dust particles (contain more than 50% dust particles with an insignificant content of clay and calcareous particles) and the presence of large pores (macropores) in the form of vertical tubes, visible to the naked eye. These soils in a dry state have significant porosity - up to 40% and have sufficient strength, but when moistened they can produce large precipitation under load. They refer to subsidence soils (under the influence of external factors and their own weight they give a significant subsidence) and when erecting buildings on them, they require proper protection of the foundations from moisture. With organic impurities (plant soil, silt, peat, bog peat) they are heterogeneous in composition, loose, and have significant compressibility.

They are not suitable as natural foundations for buildings (when moistened, they completely lose strength and large, often uneven, deformations - subsidence) occur. When using loess as a base, it is necessary to take measures to eliminate the possibility of its soaking.

2.3.3. Quicksands

Quicksands- these are soils that, when opened, begin to move like a viscous-flowing body; they are formed by fine-grained silty sands with silty and clayey impurities saturated with water. When liquefied, they become highly mobile, in fact, they turn into a liquid state.

Distinguish true quicksand And pseudoquicks. True quicksand characterized by the presence of silt-clay and colloidal particles, high porosity (> 40%), low water yield and filtration coefficient, a feature of thixotropic transformations, floating at a humidity of 6 - 9% and transition to a fluid state at 15 - 17%. Pseudo-swimmers– sands that do not contain fine clay particles, are completely saturated with water, easily release water, are permeable, turning into a quicksand state at a certain hydraulic gradient.

They are of little use as natural bases.

2.4. Biogenic soils

Biogenic soils characterized by a significant content of organic substances. These include peaty soils, peats and sapropels. Peaty soils include sandy and silty-clayey soils containing 10 - 50% (by weight) of organic matter. If there are more than 50%, then it is peat. Sapropels are freshwater silts.

2.5. Soils

Soils- these are natural formations that make up the surface layer of the earth’s crust and have fertility.

Soils And biogenic soils cannot serve as a foundation for a building or structure. The first ones are cut and used for farming purposes, the second ones require special measures to prepare the base.

2.6. Bulk soils

Bulk– formed artificially when filling ravines, ponds, landfill sites, etc. or soils of natural origin with a disturbed structure as a result of soil movement. The properties of such soils are very different and depend on many factors (type of source material, degree of compaction, homogeneity, etc.). They have the property of uneven compressibility, and in most cases they cannot be used as natural foundations for buildings. Bulk soils are very heterogeneous; in addition, various organic and inorganic materials significantly worsen its mechanical properties. Even in the absence of organic impurities, in some cases they remain weak for many decades.

As a foundation for buildings and structures, fill soil is considered in each individual case, depending on the nature of the soil and the age of the embankment. For example, sands that have compacted for more than three years, especially sands, can serve as the basis for the foundation of small buildings, provided that there are no plant remains and household waste in it.

In practice, there are also alluvial soils formed as a result of the cleaning of rivers and lakes. These soils are called refilled fill soils . They are a good foundation for buildings.

You watched: Construction classification of soils. Types of soils.

The classification of soils includes the following taxonomic units, distinguished by groups of characteristics:

Class - according to the general nature of structural connections;

Group - according to the nature of structural connections (taking into account their strength);

Subgroup - by origin and conditions of education;

Type – according to material composition;

Type – by soil name (taking into account particle sizes and property indicators);

Varieties - according to quantitative indicators of the material composition, properties and structure of soils.

The names of soils must contain information about their geological age in accordance with local stratigraphic schemes adopted in the prescribed manner.

It is allowed to introduce additions and changes to the characteristics of soils according to the varieties provided for by this standard in cases where new quantitative criteria for identifying soil varieties appear and as a result of scientific and technical developments.

The classification of soils according to GOST 25100-95 is shown in abbreviated form in Table 3.1.

Rocky soils. Their structures have rigid crystalline bonds, for example, granite, limestone. The class includes two groups of soils: 1) rocky, which includes three subgroups of rocks: igneous, metamorphic, sedimentary cemented and chemogenic; 2) semi-rocky in the form of two subgroups - igneous outpouring and sedimentary rocks such as marl and gypsum. The division of soils of this class into types is based on the characteristics of the mineral composition, for example, silicate type - gneisses, granites, carbonate type - marble, chemogenic limestones. Further division of soils into varieties is carried out according to properties: according to strength - granite - very strong, volcanic tuff - less durable; In terms of solubility in water, quartzite is very water-resistant, limestone is not water-resistant.

Dispersed soils. This class includes only sedimentary rocks. The class is divided into two groups - cohesive and non-cohesive soils. These soils are characterized by mechanical and water-colloidal structural bonds. Cohesive soils are divided into three types - mineral (clayey formations), organomineral (silts, sapropels, etc.) and organic (peat). Non-cohesive soils are represented by sands and coarse rocks (gravel, crushed stone, etc.). Soil varieties are based on density, salinity, granulometric composition and other indicators.

Frozen soils. All soils have cryogenic structural bonds, i.e. the cement of the soil is ice. The class includes almost all rocky, semi-rocky and cohesive soils located in conditions of negative temperatures. To these three groups is added a group of icy soils in the form of above-ground and underground ice. The types of frozen soils are based on icy (cryogenic) structures, salinity, temperature and strength properties, etc.

Technogenic soils. These soils are, on the one hand, natural rocks - rocky, dispersed, frozen, which for some purpose were subjected to physical or physico-chemical influence, and on the other hand, artificial mineral and organomineral formations formed in the process of domestic and industrial activities. human activity. The latter are often called anthropogenic formation. Unlike other classes, this class is first divided into three subclasses, and after that each subclass, in turn, is divided into groups, subgroups, types, types and varieties of soils. Varieties of technogenic soils are distinguished on the basis of specific properties.

Table 3.1

Class of rocky and dispersed soils

Class	Groups	Subgroup	Type	View	Varieties
Rocky (with rigid structural bonds - crystallization and cementation)	Rocky	Igneous	Intrusive	Silicate	Ultra basic composition	Peridotites, dunites, pyroxenites	They are distinguished by: 1 uniaxial compressive strength in a water-saturated state; 2 soil skeleton density; 3 weathering coefficient; 4 degrees of softening; 5 degrees of solubility; 6 degrees of water permeability; 7 degrees of salinity; 8 structure and texture; 9 temperature
Main cast	Gabbro, norites, anorthosites, diabases, diabase porphyrites, dolerites
Average composition	Diorites, syenites, porphyrites, orthoclase porphyries
Sour composition	Granites, quartz granodiorites, syenites, diorites, quartz porphyries, quartz porphyrites
Rocky		Effusive	Silicate	Main cast	Basalts, dolerites	They are distinguished by: 1 uniaxial compressive strength in a water-saturated state; 2 soil skeleton density; 3 weathering coefficient;
Average composition	Andesites, volcanic-clastic soils*, obsidians, trachytes

Continuation of the table. 3.1

Class	Groups	Subgroup	Type	View	Varieties
Rocky (with rigid structural bonds - crystallization and cementation					Sour composition	Liparites, dacites, rhyolites	4 degrees of softening; 5 degrees of solubility; 6 degrees of water permeability; 7 degrees of salinity; 8 structure and texture; 9 temperature
Metamorphic	Silicate	Gneisses, schists, quartzites
Carbonate	Marbles, hornfels, skarns
Ferrous	Iron ores
Sedimentary intrusive	Silicate	Sandstones, conglomerates, breccias, tuffites
Carbonate	Limestones*, dolomites
Sedimentary effusive	Silicate	Volcanogenic-clastic soils*
Semi-rocky	Igneous effusive	Silicate	Volcanic tuffs
Sedimentary	Silicate	Mudstones, siltstones, sandstones
Siliceous	Opoka, tripoli, diatomite

Continuation of the table. 3.1

Class	Groups	Subgroup	Type	View	Varieties
			Carbonate	Chalk, marls, limestones*
Sulfate	Gypsum, anhydrite
Halide	Halites, carnolites
Dispersed (with mechanical and water-colloidal structural bonds)	Messengers	Sedimentary	Mineral	Silicate Carbonate Ferrous Polymineral	Clay soils	They are distinguished by: 1 granulometric composition (coarse soils and sands); 2 number of plasticity and granulometric composition (clayey soils and silts); 3 fluidity index (clayey soils); 4 relative swelling strain without load 5 relative subsidence strain (clayey soils);
Organo-mineral	Silts Sapropels Peat soils
Organic	Peats, etc.

* Soils of the same type, differing in uniaxial compressive strength

Continuation of the table. 3.1

Note - Soils (crushed stone, woody soil, sandy soil, clayey soil, peat soil, etc.) are identified based on a set of characteristics as the corresponding type and variety of soil.

Table 3.2

Class natural frozen soils

Class	Group	Subgroup	Type	View	Varieties
Frozen (with cryogenic structural bonds)	Rocky	Frozen	Intrusive Effusive Metamorphic and sedimentary	Ice mineral	All types of igneous, metamorphic and sedimentary	They are distinguished by: 1 ice content due to visible ice inclusions; 2 temperature-strength properties; 3 degrees of salinity; 4 cryogenic texture
Semi-rock	Effusive Sedimentary
	Sedimentary	Ice mineral	The same as for dispersed soils
Ice organo-mineral
Ice organic
Icy	Constitutional (in-ground)		Ice – segregation, injection, glacial
Buried	Ice	Ice – ice, river, lake, sea, bottom, infiltration (snow)
		Cave veins		Ice – veined, re-veined

Table 3.3.

Class of technogenic soils (rocky, dispersed)

Class	Group	Subgroup	Type	View	Varieties
	rocky soils	Rocky and semi-rocky soils			silicate, carbonate	granites, basalts, quartzites, sandstones, marbles, limestones, marls, etc.
dispersed soils	Messengers		Changed by physical influence	silicate, carbonate, polymineral, organomineral, etc.	crushed rock and dispersed rocks (clayey, sand, etc.)
Changed by physico-chemical influence
Incoherent	Natural rocks, displaced formations	Bulk
Alluvial
Anthropogenic formations	Bulk	Waste from industrial and economic activities	Household waste
Alluvial	Industrial waste: construction waste, slag, sludge, ashes, cinders, etc.

Continuation of the table. 3.3

Class	Group	Subgroup	Type	View	Varieties
Technogenic soils (with various structural connections)	Frozen	Rocky Half-rocky	Natural formations modified in natural conditions			All types of natural rocky soils	They are distinguished as corresponding varieties of classes of natural soils, taking into account the specific features and properties of technogenic soils
Changed by chemical and physical influence
Messengers	Natural formations modified in natural conditions	Changed by physical (thermal) influence	The same as for natural frozen soils	All types of natural dispersed soils
Changed by chemical and physical influence
Incoherent	Natural displaced formations	Bulk Alluvial	Changed by physical (thermal) or chemical-physical effects		Household waste Industrial waste: construction waste, slag, sludge, cinders, ash sludge, etc. Artificial ice
Icy	Anthropogenic formations	Bulk Alluvial Frozen

The physical properties of the underlying soils are examined in terms of their ability to carry the load of the house through its foundation.

The physical properties of soil change depending on the external environment. They are affected by: humidity, temperature, density, heterogeneity and much more, therefore, to assess the technical suitability of soils, we will examine their properties, which are unchanged and which can change when the external environment changes:

• cohesion (adhesion) between soil particles;
• size, shape of particles and their physical properties;
• homogeneity of composition, the presence of impurities and their effect on the soil;
• coefficient of friction of one part of the soil against another (shear of soil layers);
• water permeability (water absorption) and changes in bearing capacity with changes in soil moisture;
• water holding capacity of the soil;
• solubility and solubility in water;
• plasticity, compressibility, loosening ability, etc.

Soils: types and properties

Soil classes

Soils are divided into three classes: rocky, dispersed and frozen (GOST 25100-2011).

• Rocky soils- igneous, metamorphic, sedimentary, volcanogenic-sedimentary, eluvial and technogenic rocks with rigid crystallization and cementation structural bonds.
• Dispersive soils- sedimentary, volcanogenic-sedimentary, eluvial and technogenic rocks with water-colloidal and mechanical structural bonds. These soils are divided into cohesive and non-cohesive (loose). The class of dispersion soils is divided into groups:
  • mineral- coarse-clastic, fine-clastic, silty, clayey soils;
  • organomineral- peat sands, silts, sapropels, peat clays;
  • organic- peats, sapropels.
• Frozen soils- these are the same rocky and dispersive soils, additionally having cryogenic (ice) bonds. Soils in which only cryogenic bonds are present are called icy.

Based on their structure and composition, soils are divided into:

• rocky;
• coarse clastic;
• sandy;
• clayey (including loess-like loams).

Mainly there are varieties of sandy and clayey varieties, which are very diverse both in particle size and in physical and mechanical properties.

According to the degree of occurrence, soils are divided into:

• top layers;
• average depth;
• deep.

Depending on the type of soil, the base can be located in different layers of soil.

The top layers of soil are exposed to atmospheric influences (wetting and drying, weathering, freezing and thawing). This impact changes the condition of the soil, its physical properties and reduces the resistance to loads. The only exceptions are rocky soils and conglomerates.

Therefore, the foundation of the house must be located at a depth with sufficient load-bearing characteristics of the soil.

Classification of soils by particle size is determined by GOST 12536

Particles	Factions	Size, mm
Large debris
Boulders*, blocks	large	> 800
	medium size	400-800
	small	200-400
Pebbles*, crushed stone	large	100-200
	medium size	60-100
	small	10-60
Gravel*, debris	large	4-10
	small	2-4
Small debris
Sand	very large	1-2
	large	0,5-1
	medium size	0,25-0,5
	small	0,1-0,25
	very small	0,05-0,1
suspension
Dust (silt)	large	0,01-0,05
	small	0,002-0,01
Colloids
Clay		< 0,002

* Names of large fragments with rolled edges.

Measured soil characteristics

To calculate the load-bearing characteristics of the soil, we need measured soil characteristics. Here are some of them.

Specific gravity of soil

Specific gravity of soil γ is called the weight of a unit volume of soil, measured in kN/m³.

The specific gravity of the soil is calculated through its density:

ρ - soil density, t/m³;
g is the acceleration of gravity, taken equal to 9.81 m/s².

Density of dry (skeletal) soil

Density of dry (skeletal) soil ρ d- natural density minus the mass of water in the pores, g/cm³ or t/m³.

Set by calculation:

where ρ s and ρ d are, respectively, the density of particles and the density of dry (skeleton) soil, g/cm³ (t/m³).

Accepted particle density ρ s (g/cm³) for soils

Porosity coefficient e, for sandy soils of different densities

Degrees of soil moisture

Degree of soil moisture S r- the ratio of the natural (natural) soil moisture W to the humidity corresponding to the complete filling of the pores with water (without air bubbles):

where ρ s is the density of soil particles (density of the soil skeleton), g/cm³ (t/m³);
e - soil porosity coefficient;
ρ w - density of water, taken equal to 1 g/cm³ (t/m³);
W is the natural soil moisture, expressed in fractions of a unit.

Soils by moisture level

Soil plasticity

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Plastic soil- its ability to deform under external pressure without breaking the continuity of the mass and maintain its given shape after the deforming force ceases.

To establish the ability of the soil to assume a plastic state, determine the humidity, which characterizes the boundaries of the plastic state of the soil of fluidity and rolling.

Yield limit W L characterizes the humidity at which the soil changes from a plastic state to a semi-liquid - fluid state. At this humidity, the connection between particles is disrupted due to the presence of free water, as a result of which soil particles are easily displaced and separated. As a result, the adhesion between particles becomes insignificant and the soil loses its stability.

Rolling limit W P corresponds to the humidity at which the soil is on the border of transition from a solid to a plastic state. With a further increase in humidity (W > W P), the soil becomes plastic and begins to lose its stability under load. The yield limit and the rolling limit are also called the upper and lower limits of plasticity.

Having determined the humidity at the border yield and rolling boundary, calculate the soil plasticity number I P. The plasticity number is the moisture interval within which the soil is in a plastic state, and is defined as the difference between the yield limit and the rolling boundary of the soil:

I Р = W L - W P

The higher the plasticity number, the more plastic the soil. The mineral and grain composition of the soil, the shape of the particles and the content of clay minerals significantly influence the plasticity limits and plasticity number.

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

Fluidity of clay soils

Show fluidity I L expressed in fractions of a unit and is used to assess the condition (consistency) of silty-clayey soils.

Determined by calculation from the formula:

I L =	W - Wp
	I r

where W is natural (natural) soil moisture;
W p - humidity at the plasticity boundary, in fractions of unity;
I p - plasticity number.

Flow index for soils of different densities

Rocky soils

Rocky soils are monolithic rocks or in the form of a fractured layer with rigid structural connections, occurring in the form of a continuous massif or separated by cracks. These include igneous (granites, diorites, etc.), metamorphic (gneisses, quartzites, schists, etc.), cemented sedimentary (sandstones, conglomerates, etc.) and artificial.

They hold compressive loads well even in a water-saturated state and at subzero temperatures, and are also insoluble and do not soften in water.

They are a good base for foundations. The only difficulty is the development of rocky soil. The foundation can be erected directly on the surface of such soil, without any opening or deepening.

Coarse soils

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Coarse - loose fragments of rocks with a predominance of fragments larger than 2 mm in size (over 50%).

Based on their granulometric composition, coarse soils are divided into:

• boulder d>200 mm (with a predominance of unrounded particles - blocky),
• pebble d>10 mm (with unrounded edges - crushed stone)
• gravel d>2 mm (with unrounded edges - wood). These include gravel, crushed stone, pebbles, and debris.

These soils are a good foundation if there is a dense layer underneath them. They shrink slightly and are reliable foundations.

If coarse-grained soils contain sand filler of more than 40% or clay filler of more than 30% of the total mass of air-dry soil, the name of the type of filler is added to the name of the coarse-grained soil and the characteristics of its condition are indicated. The type of filler is determined after removing particles larger than 2 mm from coarse soil. If the fragmentary material is represented by shells in an amount of ≥ 50%, the soil is called shell-like; if from 30 to 50%, shells are added to the name of the soil.

Coarse soil can be heaving if the fine component is silty sand or clay.

Conglomerates

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Conglomerates are coarse-grained rocks, a group of destroyed rocks, consisting of individual stones of different fractions, containing more than 50% fragments of crystalline or sedimentary rocks, not interconnected or cemented by foreign impurities.

As a rule, the bearing capacity of such soils is quite high and can support the weight of a house of several floors.

Cartilaginous soils

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Cartilaginous soils are a mixture of clay, sand, broken stones, crushed stone and gravel. They are poorly washed out by water, are not subject to swelling and are quite reliable.

They don't shrink or blur. In this case, it is recommended to lay a foundation with a depth of at least 0.5 meters.

Dispersive soils

Mineral dispersion soil consists of geological elements of various origins and is determined by the physicochemical properties and geometric sizes of the particles of its components.

Sandy soils

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Sandy soils are a product of rock destruction; they are a loose mixture of quartz grains and other minerals formed as a result of the weathering of rocks with particle sizes from 0.1 to 2 mm, containing clays of no more than 3%.

According to particle size, sandy soils can be:

• gravelly (25% of particles larger than 2 mm);
• large (50% of particles by weight are larger than 0.5 mm);
• medium size (50% of particles by weight are larger than 0.25 mm);
• small (particle sizes - 0.1-0.25 mm)
• dusty (particle sizes 0.005-0.05 mm). They are close in their manifestations to clayey soils.

Based on density they are divided into:

• dense;
• medium density;
• loose.

The higher the density, the stronger the soil.

Physical properties:

• high flowability, since there is no adhesion between individual grains.
• easy to develop;
• good water permeability, allows water to pass through well;
• do not change in volume at different levels of water absorption;
• freeze slightly, not heaving;
• under load they tend to become very compact and sag, but in a fairly short time;
• not plastic;
• easy to compact.

Dry, clean (especially coarse) quartz sand can withstand heavy loads. The larger and purer the sand, the greater the load the base layer can withstand. Gravelly, coarse and medium-sized sands are significantly compacted under load and freeze slightly.

If the sands lie evenly with sufficient density and thickness of the layer, then such soil is a good basis for the foundation and the larger the sand, the greater the load it can take. It is recommended to lay the foundation at a depth of 40 to 70 cm.

Fine sand diluted with water, especially with admixtures of clay and silt, is unreliable as a base. Silty sands (particle size from 0.005 to 0.05 mm) weakly support the load, as the base requires strengthening.

Sandy loam

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Sandy loam - soils in which clay particles less than 0.005 mm in size are contained in the range from 5 to 10%.

Quicksand are sandy loams whose properties are similar to silty sands, containing a large amount of dusty and very fine clay particles. With sufficient water absorption, dusty particles begin to play the role of a lubricant between large particles, and some types of sandy loam become so mobile that they flow like liquid.

There are true quicksands and pseudo quicksands.

True quicksand characterized by the presence of silt-clay and colloidal particles, high porosity (> 40%), low water yield and filtration coefficient, a feature of thixotropic transformations, floating at a humidity of 6 - 9% and transition to a fluid state at 15 - 17%.

Pseudo-swimmers- sands that do not contain fine clay particles, are completely saturated with water, easily release water, are permeable, turning into a quicksand state at a certain hydraulic gradient.

Quicksand are practically unsuitable for use as foundation bases.

Clay soils

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Clays are rocks consisting of extremely small particles (less than 0.005 mm), with a small admixture of small sand particles. Clay soils were formed as a result of physical and chemical processes that occurred during the destruction of rocks. Their characteristic property is the adhesion of the smallest soil particles to each other.

Physical properties:

• low water-permeability properties, therefore they always contain water (from 3 to 60%, usually 12-20%).
• increase in volume when wet and decrease when dry;
• depending on humidity, they have significant particle cohesion;
• Clay compressibility is high, compaction under load is low.
• plastic only within a certain humidity; at lower humidity they become semi-solid or solid, at higher humidity they turn from a plastic state into a fluid one;
• washed away by water;
• heaving.

According to the absorbed water, clays and loams are divided into:

• hard,
• semi-solid,
• tight-plastic,
• soft plastic,
• fluid-plastic,
• fluid.

Settlement of buildings on clay soils lasts longer than on sandy soil. Clay soils with sandy layers liquefy easily and therefore have low bearing capacity.

Dry, tightly compacted clay soils with a large layer thickness can withstand significant loads from structures if there are stable underlying layers underneath them.

Clay that has been compacted for many years is considered a good base for the foundation of a house.

But such clay is rare, because... in its natural state it is almost never dry. The capillary effect present in fine-textured soils means that the clay is almost always wet. Moisture can also penetrate through sandy impurities in clay, so moisture absorption in clay occurs unevenly.

Heterogeneity of humidity when the soil freezes leads to uneven heaving at subzero temperatures, which can lead to deformation of the foundation.

All types of clay soils, as well as dusty and fine sands, can be heaving.

Clay soils are the most unpredictable for construction.

They can erode, swell, shrink, and swell when frozen. Foundations on such soils are built below the freezing mark.

In the presence of loess and silty soils, it is necessary to take measures to strengthen the foundation.

Macroporous clays

Clay soils, which in their natural composition have pores visible to the naked eye and significantly larger than the soil skeleton, are called macroporous. Macroporous soils include loess soils (more than 50% dust particles), most common in the south of the Russian Federation and the Far East. In the presence of moisture, loess-like soils lose stability and become wet.

Loams

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Loams are soils in which clay particles less than 0.005 mm in size are contained in the range from 10 to 30%.

In terms of their properties, they occupy an intermediate position between clay and sand. Depending on the percentage of clay, loams can be light, medium or heavy.

Such soil as loess belongs to the group of loams, contains a significant amount of dust particles (0.005 - 0.05 mm) and water-soluble limestones, etc., is very porous and shrinks when wet. When frozen it swells.

In a dry state, such soils have significant strength, but when moistened, the soil softens and becomes sharply compacted. As a result, significant precipitation occurs, severe distortions and even destruction of structures erected on it, especially those made of brick.

Thus, in order for loess-like soils to serve as a reliable foundation for structures, it is necessary to completely eliminate the possibility of their soaking. To do this, it is necessary to carefully study the groundwater regime and the horizons of their highest and lowest standing.

Silt (silty soils)

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Silt - formed at the initial stage of its formation in the form of structural sediments in water, in the presence of microbiological processes. For the most part, such soils are located in peat mining areas, swampy and wetlands.

Silt - silty soils, water-saturated modern sediment of predominantly marine areas, containing organic matter in the form of plant residues and humus, the content of particles less than 0.01 mm is 30-50% by weight.

Properties of silty soils:

• Strong deformability and high compressibility and, as a result, negligible resistance to loads and unsuitability for their use as a natural base.
• Significant influence of structural bonds on mechanical properties.
• Insignificant resistance to friction forces, which makes it difficult to use pile foundations;
• Organic (humic) acids in sludge act destructively on concrete structures and foundations.

The most significant phenomenon that occurs in silty soils under the influence of external load, as mentioned above, is the destruction of their structural connections. Structural bonds in silt begin to collapse under relatively minor loads, but only at a certain external pressure value that is quite specific for a given silty soil does an avalanche (massive) disruption of structural bonds occur, and the strength of the silty soil sharply decreases. This amount of external pressure is called the “structural strength of the soil”. If the pressure on silty soil is less than the structural strength, then its properties are close to those of a low-strength solid, and, as relevant experiments show, neither the compressibility of silt nor its shear resistance are practically independent of natural moisture. In this case, the angle of internal friction of the silty soil is small, and the adhesion has a well-defined value.

The sequence of construction of foundations on silty soils:

• These soils are “excavated” and replaced layer by layer with sandy soil;
• A stone/crushed stone cushion is poured, its thickness is determined by calculation; it is necessary that the pressure exerted on the surface of the silty soil from the structure and the cushion is not dangerous for the silty soil;
• After this, the structure is erected.

Sapropel

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Sapropel is a freshwater sludge formed at the bottom of stagnant reservoirs from decay products of plant and animal organisms and containing more than 10% (by weight) of organic matter in the form of humus and plant residues.

Sapropel has a porous structure and, as a rule, a fluid consistency, high dispersion - the content of particles larger than 0.25 mm usually does not exceed 5% by weight.

Peat

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Peat is an organic soil formed as a result of the natural death and incomplete decomposition of marsh plants under conditions of high humidity and lack of oxygen and containing 50% (by weight) or more organic substances.

They contain a large amount of plant sediments. Based on the amount of their content, they are distinguished:

• slightly peaty soils (relative content of plant sediments is less than 0.25);
• medium peat (from 0.25 to 0.4);
• heavily peated (from 0.4 to 0.6) and peats (over 0.6).

Peat bogs are usually very wet, have strong uneven compressibility and are practically unsuitable as a foundation. Most often they are replaced with more suitable bases, for example, sand.

Peaty soil

Peat soil - sand and clay soil containing from 10 to 50% (by weight) peat.

Soil moisture

Due to the capillary effect, soils with a fine structure (clay, silty sand) are moist even when the groundwater level is low.

The water rise can reach:

• in loams 4 - 5 m;
• in sandy loams 1 - 1.5 m;
• in dusty sands 0.5 - 1 m.

Conditions for slightly heaving soil

Relatively safe conditions for the soil to be considered slightly heaving when the groundwater is located below the calculated freezing depth:

• in silty sands at 0.5 m;
• in sandy loams by 1 m;
• in loams at 1.5 m;
• in clays at 2 m.

Conditions for medium heaving soil

The soil can be classified as medium heaving when the groundwater is located below the calculated freezing depth:

• in sandy loams by 0.5 m;
• in loams per 1 m;
• in clays at 1.5 m.

Conditions for highly heaving soil

The soil will be highly heaving if the groundwater level is higher than for medium heaving soils.

Determining soil type by eye

Even a person far from geology will be able to distinguish clay from sand. But not everyone can determine by eye the proportion of clay and sand in the soil. What type of soil is loam or sandy loam? And what is the percentage of pure clay and silt in such soil?

First, inspect the neighboring residential areas. Neighbors' foundation foundation experience can provide useful information. Leaning fences, deformations of foundations when they are laid shallow, and cracks in the walls of such houses indicate heaving soils.

Then you need to take a soil sample from your site, preferably closer to the site of your future home. Some people advise making a hole, but you can’t dig a narrow hole deep, and what should you do with it then?

I propose a simple and obvious option. Start your construction by digging a hole for a septic tank.

You will get a well with sufficient depth (at least 3 meters, more can be) and width (at least 1 meter), which provides a lot of advantages:

• space for taking soil samples from different depths;
• visual inspection of the soil section;
• the ability to test the soil for strength without removing the soil, including the side walls;
• You don't need to dig the hole back in.

Just install concrete rings in the well in the near future so that the well does not crumble from rain.

Determining soil by appearance

Dry rock condition

Clay	It is hard in pieces and breaks into separate lumps when struck. Lumps are crushed with great difficulty. It is very difficult to grind into powder.
Loams	Lumps and pieces are relatively hard, and upon impact they crumble, forming fines. The mass rubbed on the palm does not give the feeling of a homogeneous powder. There is little sand to the touch when rubbing. Lumps are crushed easily.
Sandy loam	The adhesion between particles is weak. The lumps easily crumble under hand pressure and when rubbed, a heterogeneous powder is felt, in which the presence of sand is clearly felt. When rubbed, silty sandy loam resembles dry flour.
Sand	Sandy self-disintegrating mass. When rubbed in the palms, it feels like a sandy mass; large sand particles predominate.

Wet rock condition

Clay	Plastic, sticky and smearing	When squeezed, the ball does not form cracks along the edges. When rolled out, it produces a strong and long cord with a diameter of< 1 мм.
Loams	Plastic	When squeezed, the ball forms a cake with cracks along the edges. No long cord is formed.
Sandy loam	Weakly plastic	A ball is formed, which crumbles when pressed lightly. Does not roll into a cord or is difficult to roll and falls apart easily.
Sand	When over-moistened, it turns into a fluid state.	Does not roll into a ball or cord.

Water clarification method

A method for determining the type of soil by the rate of water clarification in 1 minute in a test tube (or glass) into which a pinch of soil is placed.

Type of foundation from the ground

• Peat - pile foundation.
• Dusty sands, viscous clays - recessed foundation with waterproofing.
• Fine and medium sands, hard clays - shallow foundation.
• In wet soils (clay, loam, sandy loam or silty sand), the depth of the foundation is greater than the calculated freezing depth.