Dust-clay soils, depending on the amount of water they contain, can have a consistency (dough density) from solid to fluid. To determine the consistency, the characteristic moisture content of silty clay soils is found, which are called the rolling boundary and the yield boundary.
The rolling boundary is the moisture content of the soil, at which it loses its ability to roll into a cord with a diameter of 2..3 mm.
The yield point is the soil moisture at which the standard cone is immersed in the sample to a depth of 10 mm.
Rice. 1.4. Determining the border of soil rolling
The plasticity number of the soil is the difference between the yield boundary and the rolling boundary:
(1.18)
The consistency of silt-clay soil is estimated by the fluidity index:
(1.19)
Table 1.5. Condition of clays and loams
For sandy loam, due to the low accuracy of determining the values and, only three states are distinguished: solid, plastic, and fluid.
Table 1.6. Sandy loam condition
In the group of silt-clay soils, loess soils and silts are distinguished - they have specific unfavorable properties.
Loess soils contain more than 50% of silt particles with the presence of salts, mainly calcium carbonate, have a predominantly macroporous structure and belong to the category of structurally unstable subsidence soils. Subsidence is a rapidly developing settlement caused by a sharp change in the structure of the soil. Significant precipitation in violation of the structure of subsiding soils is due to the fact that under natural conditions they are undercompacted. In the process of their formation, there is no complete compaction due to the action of its own weight due to the formation of new structural bonds. Such soils become macroporous and, under certain external influences (soaking, vibration), which destroy the bonds that have arisen, they can be additionally compacted, which causes significant precipitation. The possibility of manifestation of subsidence properties of soils is preliminarily assessed by the degree of their moisture content and the subsidence index, which is determined by the formula:
where: e - coefficient of porosity of natural soil; - coefficient of porosity corresponding to moisture content at the yield point (1.16).
Comparison of the natural moisture content of the soil with the moisture content at the boundary of rolling allows you to establish its state in terms of fluidity
,
(1.11)
according to which clay soils are divided into the following varieties:
hard .......... 
<
0
plastic ............... from 0 to 1 inclusive
flowing..................>1
Loams and clays:
solid ................................ 
<
0
semi-solid ........................ from 0 to 0.25
hard-plastic .............. from 0.25 to 0.5
soft plastic ................ from 0.5 to 0.75
fluid plastic .............. from 0.75 to 1
flowing.................................>1
Maximum density and optimum soil moisture
In the process of erecting earthworks and planning territories, soils have to be compacted. At the same time, the strength of the soil increases, its water permeability and capillarity decrease. The maximum degree of compaction is required in the upper layers of the embankment, in which the greatest stresses from external loads occur.
The degree of compaction is estimated by the value of the compaction factor. By compacting soils with different moisture content with the same compaction work, different values of the dry soil density are obtained. Moisture at which the maximum density of dry soil is reached 
with standard sealing, is called optimal
W opt .
In vitro W opt and 
determined using the Soyuzdornia device (Fig. 1.7). The method consists in establishing the dependence of the density of dry soil on its moisture content during the compaction of soil samples with a constant work of compaction and a consistent increase in soil moisture. Conduct at least 5 - 6 experiments at different soil moisture. The soil is compacted in the glass of the device in layers by blows of a 2.5 kg weight falling from a height of 30 cm. Each soil layer (3 layers in total) is compacted by 40 blows. After compaction in each experiment, determine 
and 
and build a graph 
property 
(Fig. 1.8).
The graph determines the humidity at which the maximum density of dry soil is achieved by standard compaction. 
. The degree of compaction of an earthwork is estimated by the value of the compaction coefficient
,
(1.12)
where 
- coefficient of compaction of the soil of an earthen structure; 
is the density of dry soil; 
- the maximum density of the same dry soil with standard compaction. Value 
is set by the earthworks design in the range from 0.92 to 1.00.
test questions
1. Determination of soil according to GOST 25100-95.
2. What are the genetic types of continental deposits?
3. What are the soils made of?
4. What is meant by the structure and texture of the soil?
5. What are the features of clay minerals?
6. In what form is water found in soils?
7. What structural bonds exist in soils?
8. What are the sizes of coarse, sandy, dusty and clay particles?
9. What is called the granulometric composition of the soil?
10. How to determine the coefficient of soil heterogeneity?
11. What are the main physical characteristics of the soil?
12. How are sandy soils classified?
13. What is called the number of plasticity?
14. How are cohesive soils classified?
15.What is the turnover rate? To what extent does it change?
16. What is the standard soil compaction method used for?
1This article presents the results of laboratory studies of the characteristics of the consistency of clay soils according to the Russian and German standard methods, conducted at the Institute of Soil Mechanics of the Braunschweig University of Technology. The problems of the difference in the classification of clay soils and methods for determining the characteristics of soil consistency in accordance with Russian and German regulatory standards are considered. A comparative analysis of the effect of consistency characteristics on the classification of silty clay soils according to Russian and German standards has been carried out. It has been established that the plasticity interval according to German standards is greater than the plasticity interval according to domestic standards for the same soil, since the moisture content at the yield point, determined according to DIN, is higher than the moisture content at the yield point, determined according to GOST. A correlation dependence between these values of the upper limit of plasticity is derived.
consistency
yield point
rolling border
plasticity number
turnover rate
1. GOST 5180-84. Soils. Methods for laboratory determination of physical characteristics.
2. GOST 25100-2011. Soils. Classification.
3. DIN 18121-1 (April 1998). Baugrund, Untersuchung von Bodenproben. Wassergehalt. Teil 1: Bestimmung durch Ofentrocknung.
4. DIN 18121-2 (August 2001). Baugrund, Untersuchung von Bodenproben. Wassergehalt. Teil 2: Bestimmung durch Schnellverfahren.
5. DIN 18122-1 (Juli 1997). Baugrund, Untersuchung von Bodenproben. Zustandsgrenzen (Konsistenzgrenzen). Teil 1: Bestimmung der Flieβ- und Ausrollgrenze.
6. DIN 18122-2 (September 2000). Baugrund, Untersuchung von Bodenproben. Zustandsgrenzen (Konsistenzgrenzen). Teil 2: Bestimmung der Schrumpfgrenze.
8. DIN ISO/TS 17892-12 (January 2005). Geotechnische Erkundung und Untersuchung - Laborversuche an Bodenproben - Teil 12: Bestimmung der Zustandsgrenzen.
In the process of integration of engineering schools and the commonality of geotechnical problems being solved on the territory of different countries, the question arises of the correctness of the application of certain soil characteristics used in geotechnical calculations, determined by various methods, as well as the interpretation of the results obtained.
The basis for the description and classification of soils in both domestic and foreign standards are physical characteristics, which, due to the dispersion of soils and historical geotechnical traditions, can be interpreted differently in different countries.
Since the dispersion of the soil has a significant effect on its plasticity, then in terms of plasticity I R with a certain reliability it is possible to characterize the lithological differences of clayey soils. This assumption underlies the Russian classification. Sandy loams include soils with I R from 1 to 7 inclusive, for loams - from 7 to 17, for clays - more than 17.
In German standards, there is a slightly different classification. According to DIN, clay soil is divided into: loam, clay, loam with sand, clay with sand, i.e. there is no allocation of such a variety of clay soil as sandy loam. The type of soil is determined by the plasticity graph (Fig. 6). The graph is a straight-line relationship (A-line) expressed by the function I R=0.73( W L-20), where W L- in %. Values I R≤ 4% or below A-lines characterize loam, values I R≥ 7% and above A-line - clay. However, if the value W L less than 35% - weakly plastic soil, if W L lies in the range from 35% to 50% - medium-plastic soil, if W L more than 50% - highly plastic soil.
To quantify the state of soil consistency, the fluidity index is used I L. In German standards, there is also a consistency indicator ic, which is the inverse of I L and is used as the main indicator to describe the state of soil consistency. The classification of soils in terms of fluidity and consistency is presented in tables 1 and 2.
Table 1
Values I L for different states of clay soil consistency according to GOST
|
State of Consistency |
Soil name |
||
|
Loam and clay |
|||
|
I L>1 |
I L>1 |
||
|
Plastic |
fluid plastic |
0,75<I L≤1 |
0≤ I L≤1 |
|
soft plastic |
0,5<I L≤0,75 |
||
|
hard plastic |
0,25<I L≤0,5 |
||
|
semi-solid |
0≤ I L≤0,25 |
||
|
I L<0 |
I L<0 |
||
table 2
Values I L and Ic for various clay soil consistency states according to DIN
In German standards, the fluid-plastic state is represented by a large interval in relation to Russian standards, which leads to a discrepancy between the remaining intervals of consistency states. To determine the solid state according to DIN, there is another transition state limit - the transition limit from a semi-solid state to a solid state ws. The solid state is accepted if the value I s more than value I s corresponding ws, on the dependency graph I s/I L humidity (Fig. 1). ws determined according to DIN according to the formula:
V d- the volume of dry soil, cm 3;
m d- mass of dry soil, g;
ρ s- density of soil particles, g/cm 3 ;
ρ w- density of water, g/cm 3 .
Rice. 1. Graphical representation of the classification of clay soil conditions according to German standards
The difference in classification and the difference in methods for determining the characteristics of consistency can give different values of classification indicators, and, consequently, a different idea of this soil.
To determine the consistency parameters and compare the results, a number of experiments were carried out in the laboratory of the Institute of Soil Mechanics of the Braunschweig University of Technology using Russian and German technologies. Consistency characteristics were determined for two types of clay soil: fluid loam and semi-solid clay according to the classification in accordance with GOST.
According to Russian technology, the yield limit was determined in accordance with GOST using a balance cone (Vasiliev). The upper limit of plasticity corresponds to such a state of the soil, in which a standard cone sinks under the action of its own weight to a depth of 1 cm in 5 s.
According to the German method, Fließgrenzegerät according to DIN and Fallkegelgerät according to DIN were used to determine the yield point.
The main method for determining the yield point in Germany is the method described in DIN using the Fließgrenzegerät device, but since this method largely depends on the human factor, on the correct calibration of the device and, in addition, is very laborious, another DIN standard proposes to replace him to the method of determining the yield point using the Fallkegelgerät device.
The Fließgrenzegerät is a hard rubber block on which a copper-zinc bowl with a percussion device is mounted. The bowl is filled with soil, in which a furrow is cut. The impact device is then actuated and the bowl rapidly rises and falls. Next, the number of impacts is recorded, at which the furrow closes by at least 1 cm (Fig. 2).
Rice. 2. Determination of the yield point in the Fließgrenzegerat:
At least 4 such tests are carried out with gradual drying or additional moistening of the soil, after each experiment a soil sample weighing 15-20 g is taken to determine the moisture content and a graph of the dependence of the number of impacts on moisture content is plotted (Fig. 3). The graph is a straight line, along which the moisture content at the yield point, corresponding to 25 shocks, is determined.
Rice. 3. Graph of the dependence of the number of strokes on humidity:
a, b - respectively, for loam and clay according to the Russian classification according to
When testing using the Fallkegelgerät, as well as when testing according to GOST, the depth to which the cone sank in 5 s under its own weight is measured. The device is a tripod with a descending cone, a caliper for measuring the draft of the cone, and a special bowl for testing (Fig. 4).
Rice. 4. Determination of the yield limit in the deviceFallkegelgerät:
a) before the test b) after the test
At least 4 tests are carried out with gradual drying or additional moisture of the soil. A graph of the dependence of the cone immersion depth on humidity is constructed, according to which the yield boundary is determined, corresponding to the immersion depth of 20 mm (Fig. 5).
Rice. 5. Graph of dependence of cone immersion depth on humidity:
a, b - for loam and clay, respectively, according to the Russian classification according to
Humidity at the rolling boundary, both according to GOST and DIN, is determined in the same way. The lower limit of plasticity corresponds to such a state of the soil, in which it will begin to disintegrate into small pieces, if rolled out into a cord with a diameter of 3 mm.
Soil moisture was determined by the reference method both in accordance with GOST and in accordance with DIN by drying to constant weight in an oven at a temperature of 105°C. Existing in German standards, express methods for determining moisture, described in DIN, were not used.
The plasticity graph is shown in Figure 6.
Rice. 6. Graph of plasticity:
* type of soil depending onIRaccording to Russian classification in accordance with GOST
ST- a mixture of clay and sand, SU- a mixture of loam and sand,
TL- weakly plastic clay, UL- slightly plastic loam,
TM- medium plastic clay, UM- medium plastic loam,
TA- highly plastic clay, U.A.- highly plastic loam;
Values obtained using the Fallkegelgerät, respectively, for loam and clay according to the Russian classification according to ,
Values obtained using the Fließgrenzegerät, respectively, for loam and clay according to the Russian classification according to .
The results and classification are summarized in tables 3 and 4.
Table 3
The obtained test results for fluid loam according to the Russian classification according to
|
Regulatory document |
Soil name |
|||||
|
GOST 25100-2011 |
Fluid loam |
|||||
|
DIN ISO/TS 17892-12 |
Clay weakly plastic in a fluid state |
|||||
|
Clay, weakly plastic in a fluid-plastic state |
Table 4
Test results for semi-hard clay according to the Russian classification according to
|
Regulatory document |
Soil name |
|||||
|
GOST 25100-2011 |
Clay semi-hard |
|||||
|
DIN ISO/TS 17892-12 |
||||||
|
Highly plastic clay in a hard-plastic state |
To compare classification indicators determined by different methods and having different values, GOST shows the correlation between the yield point according to the international standard ( LL) and the yield limit according to GOST ( W L):
LL=1.48 W L - 8,3 (2)
As a result of the analysis of the obtained data, the dependence function between the same standards has a slightly different form:
LL=1.2 W L - 4,21 (3)
However, the similarly obtained relationship between DIN and GOST is very close to function (2):
LL=1.47 W L -7,45 (4)
It should be taken into account that the results were obtained on a limited amount of experimental data. Further extended studies are needed for more accurate results.
Main conclusions
- The plasticity curve used in the German code for the classification of clay soil depends on two indicators: W L and Ip, which makes it possible to determine not only the type of soil, but also its ability to exhibit plastic properties. This contributes to a more accurate assessment and classification of the soil. At the same time, there is no such type of soil as sandy loam. Instead, on the plasticity graph, the corresponding area is indicated as a mixture of clay and sand or a mixture of loam and sand.
- Moisture at the yield point W L has different meanings depending on which regulatory standard it is defined by. So, for example, W L for clay according to the Russian classification according to GOST, determined in accordance with GOST, is 6.5% less than W L the same soil, determined according to DIN, and 16.2% less than W L defined according to DIN. For loam according to the Russian classification according to GOST W L less by 1.7% and 5.6% respectively.
- Significant difference values W L talk about the different plasticity of the soil Ip and, therefore, can characterize the same soil in different ways. In addition, the difference in the flow rate I L and inconsistency of classification give a different idea of the state of the soil and, as a result, of its strength and deformability characteristics and work under loads and impacts in general.
Reviewers:
Mironov V.V., Doctor of Technical Sciences, Professor, Tyumen State University of Civil Engineering, Tyumen;
Chekardovsky M.N., Doctor of Technical Sciences, Professor, Head of the Department of Heat, Gas, Water Supply and Ventilation, FGBOU VPO TyumenGASU, Tyumen.
Bibliographic link
Pronozin Ya.A., Kalugina Yu.A. COMPARISON OF THE INFLUENCE OF THE CHARACTERISTICS OF THE CONSISTENCY ON THE CLASSIFICATION OF DUTY-CLAY SOILS ACCORDING TO THE RUSSIAN AND GERMAN NORMATIVE STANDARDS // Modern problems of science and education. - 2015. - No. 1-1 .;URL: http://science-education.ru/ru/article/view?id=19024 (date of access: 01.02.2020). We bring to your attention the journals published by the publishing house "Academy of Natural History"
Soil moisture is determined by drying a soil sample at a temperature of 105°C to constant weight. The ratio of the difference between the masses of the sample before and after drying to the mass of absolutely dry soil gives the value of moisture, expressed as a percentage or fractions of a unit. The proportion of filling the pores of the soil with water - the degree of humidity S r calculated by the formula (see table. 1.3). The moisture content of sandy soils (with the exception of silty ones) varies within small limits and practically does not affect the strength and deformation properties of these soils.
The plasticity characteristics of silty clay soils are the moisture content at the yield boundaries wland rolling w R, determined in the laboratory, as well as the plasticity number / p and the flow index II, calculated by formulas (see Table 1.3). Characteristics w L , w P and IP are indirect indicators of the composition (granulometric and mineralogical) of silty clay soils. High values of these characteristics are characteristic of soils with a high content of clay particles, as well as soils, the mineralogical composition of which includes montmorillonite.
1.3. SOIL CLASSIFICATION
The soils of the foundations of buildings and structures are divided into two classes: rocky (soils with rigid bonds) and non-rocky (soils without rigid bonds).
In the class of rocky soils, igneous, metamorphic and sedimentary rocks are distinguished, which are subdivided according to strength, softening and solubility in accordance with Table. 1.4. Rocky soils, the strength of which in a water-saturated state is less than 5 MPa (semi-rocky), include clay shales, sandstones with clay cement, siltstones, mudstones, marls, and chalks. With water saturation, the strength of these soils can decrease by 2-3 times. In addition, in the class of rocky soils, artificial - fixed in their natural occurrence, fractured rocky and non-rocky soils are also distinguished. These soils are subdivided according to the method of fixing (cementation, silicification,
 |
 |
bituminization, tarring, firing, etc.) and according to the strength limit for uniaxial compression after fixing, just like rocky soils (see Table 1.4).
Non-rocky soils are divided into coarse-clastic, sandy, silty-argillaceous, biogenic and soils.
■ Coarse-clastic soils include non-consolidated soils in which the mass of fragments larger than 2 mm is 50% or more. Sandy soils are soils containing less than 50% of particles larger than 2 mm and not possessing the property of plasticity (plasticity number / p<
The properties of coarse-grained soil with a content of sand aggregate of more than 40% and silt-clay aggregate of more than 30% are determined by the properties of the aggregate and can be established by testing the aggregate. With a lower aggregate content, the properties of coarse soil are determined by testing the soil as a whole. When determining the properties of a sand aggregate, the following characteristics are taken into account - humidity, density, porosity coefficient, and dusty-clay aggregate - additionally the plasticity number and consistency.
The main indicator of sandy soils, which determines their strength and deformation properties, is the bulk density. According to the density of addition, sands are subdivided according to the porosity coefficient e, soil resistivity during static sounding q c and conditional soil resistance during dynamic sounding q&(Table 1.7).
With a relative content of organic matter of 0.03
0.5% ■- with a sand aggregate content of 40% or more;
Sandy soils are classified as saline if the total content of these salts is 0.5% or more.
Dusty clay soils are subdivided according to the number of plasticity h(Table 1.8) and by con-
 |
 |
 |
consistency, characterized by the fluidity index 1 L(Table 1.9). Among the silty-clayey soils, it is necessary to distinguish loess soils and silts. Loess soils are macroporous soils containing calcium carbonates and capable, when soaked with water, to give a subsidence under load, easily soak and erode. Silt - water-saturated modern sediment of reservoirs, formed as a result of microbiological processes, having a moisture content exceeding the moisture content at the yield line, and a porosity coefficient, the values of which are given in table. 1.10.
Silty clay soils (sandy loam, loam and clay) are called soils with an admixture of organic substances with a relative content of these substances of 0.05
Among silt-clay soils, it is necessary to distinguish soils that exhibit specific unfavorable properties during soaking: subsidence and swelling. Subsiding soils include soils that, under the action of an external load or their own weight, when soaked with water, give a sediment (subsidence), and at the same time, the relative subsidence Ss /> 0.01. Swelling soils include soils that, when soaked with water or chemical solutions, increase in volume, and at the same time, relative swelling without load e S ! »>0.04.
In a special group in non-rocky soils, soils are distinguished that are characterized by a significant content of organic matter: biogenic (lake, marsh, alluvial-marsh). The composition of these soils includes peaty soils, peat and sapropels. Peaty soils include sandy and silty clay soils containing 10-50% (by weight) of organic matter in their composition. With an organic content of 5Q% and
 |
 |
more soil is called peat. Sapropels (Table 1.11) are freshwater silts containing more than 10% organic matter and having a porosity coefficient, as a rule, more than 3, and a flow index more than 1.
Soils are natural formations that make up the surface layer of the earth's crust and are fertile. Soils are divided according to their granulometric composition in the same way as coarse and sandy soils, and according to the number of plasticity, like silty clay soils.
Non-rocky artificial soils include soils compacted in their natural occurrence by various methods (tamping, rolling, vibration compaction, explosions, drainage, etc.), bulk and alluvial. These soils are subdivided according to the composition and characteristics of the state in the same way as natural non-rock soils.
Rocky and non-rocky soils that have a negative temperature and contain ice in their composition are classified as frozen soils, and if they are in a frozen state for 3 years or more, then they are permafrost.
1.4. SOIL DEFORMABILITY UNDER COMPRESSION
A characteristic of the deformability of soils in compression is the modulus of deformation, which is determined in field and laboratory conditions. For preliminary calculations, as well as final calculations of the foundations of buildings and structures of II and III classes, it is allowed to take the deformation modulus according to Table. 1.12 and 1.13.
Module deformations are determined by testing the soil with a static load transmitted to the stamp. Tests are carried out in pits with a rigid round stamp with an area
5000 cm 2, and below the groundwater level and at great depths - in wells with a stamp of 600 cm 2. To determine the deformation modulus, a graph of the dependence of settlement on pressure is used (Fig. 1.1), on which a linear section is selected, an averaging straight line is drawn through it and the deformation modulus is calculated E in accordance with the theory of a linearly deformable medium according to the formula
When testing soils, it is necessary that the thickness of the layer of homogeneous soil under the stamp be at least two stamp diameters.
The deformation moduli of isotropic soils can be determined in wells using a pressuremeter (Fig. 1.2). As a result of the tests, a graph of the dependence of the increase in the radius of the well on the pressure on its walls is obtained (Fig. 1.3). The deformation modulus is determined in the area of the linear dependence of deformation on pressure between the point R\, corresponding to the compression of the roughness of the borehole walls, and the point p2, after which the intensive development of plastic deformations in the soil begins. The deformation modulus is calculated
ftlOnMVJlft software
Coefficient k is determined, as a rule, by comparing pressuremetry data with the results of parallel tests of the same soil with a stamp. For structures II in III class can be taken depending on the depth of the test h the following values of the coefficients to in formula (1.2): at ft<5 м 6 = 3; при 5мk = 2; at 10 m
For sandy and silty-clay soils, it is allowed to determine the deformation modulus "based on the results of static and dynamic sounding of soils. The following are taken as indicators of sounding: in case of static sounding - soil resistance to immersion of the probe cone q c , and in dynamic sounding - conditional dynamic soil resistance to cone immersion qa, For loams and clays E-7q c and I-6#<*; для песчаных грунтов E-3q c , and the values of £ according to dynamic sounding data are given in Table. 1.14. For buildings I and II class
 |
 |
 |
 |
it is mandatory to compare the sounding data with the results of testing the same soils with stamps. For class III structures, it is allowed to determine E based on sounding results.
1.4.2. Determination of the deformation modulus in the laboratory
Under laboratory conditions, compression devices (odometers) are used, in which the soil sample is compressed without the possibility of lateral expansion. The deformation modulus is calculated at the selected pressure interval Dr = P2-Pi of the test schedule (Fig. 1.4) according to the formula
The pressure pi corresponds to natural, and p2 - to the expected pressure under the base of the foundation.
The values of the deformation moduli according to compression tests are obtained for all soils (except for highly compressible ones) underestimated, so they can be used for a comparative assessment of compressibility.
site soils or to assess compressibility heterogeneity. When calculating the settlement, these data should be corrected on the basis of comparative tests of the same soil in the field with a stamp. For Quaternary sandy loams, loams and clays, correction factors can be taken t(Table 1.16), while the values Eovts must be determined in the pressure range of 0.1-0.2 MPa.
1.5. SOIL STRENGTH
Soil resistance to shear is characterized by tangential stresses in the limit state, when soil destruction occurs. Relationship between limiting tangents m and normal to shear areas a stresses is expressed by the Mohr-Coulomb strength condition
 |
1.5.1. Determination of strength characteristics in laboratory conditions
In the practice of soil research, the method of cutting the soil along a fixed
planes in devices of a single-plane cut. To receive<р и с необходимо провести срез не менее трех образцов грунта at different values of vertical load. According to the values of shear resistance t obtained in the experiments, a graph of the linear dependence T = f(a) is plotted and the angle of internal friction φ and specific adhesion are found with(Fig. 1.5). Once-
There are two main experimental schemes: a slow cut of a soil sample pre-compacted to complete consolidation (consolidated-drained test) and a fast cut without pre-compaction (some kind of consolidated-undrained test).
 |
Chapter 2. ENGINEERING AND GEOLOGICAL SURVEYS
GENERAL INFORMATION
Engineering-geological surveys - an integral part of the complex of works performed to provide building design with initial data on the natural conditions of the construction area (site), as well as predicting changes in the natural environment that may occur during the construction and operation of structures. When conducting engineering and geological surveys, soils are studied as the foundations of buildings and structures, groundwater, physical and geological processes and phenomena (karst, landslides, mudflows, etc.) - Engineering and geological surveys are accompanied by engineering and geodetic surveys, the object of study of which are topographic conditions construction area, and engineering and hydrometeorological surveys, during which surface water and climate are studied.
Conducting surveys is regulated by normative documents and standards. General requirements for surveys are given in SNiP P-9-78, and survey requirements for certain types of construction are in instructions SN 225-79 and SN 211-62. Taking into account the specifics of the design of pile foundations, the main requirements for surveys for them are given in SNiP 11-17-77 and in the "Guidelines for the design of pile foundations". Determination of the basic building properties of soils is regulated by the standards specified in clause 2.4.
Engineering-geological surveys should be carried out, as a rule, by territorial surveying, as well as specialized surveying and design and survey organizations. They are allowed to be carried out by design organizations that have been granted such a right in the prescribed manner.
2.2. REQUIREMENTS TO THE TERMS OF REFERENCE AND SURVEY PROGRAM
Planning and execution of surveys are carried out on the basis of the terms of reference for the production of surveys, compiled by the design organization - the customer. When drawing up the terms of reference, it is necessary to determine which materials characterizing the natural conditions of construction,
will be required for the development of the project, and on this basis, obtain permission from the relevant authorities to conduct surveys for this object. The permit issuing authority may indicate the need to use (in order to avoid duplication) the materials of previously completed work at its disposal on the territory of the facility being designed, which should be reflected in the terms of reference. If there are materials of previously completed surveys for the projected object, then they are transferred to the survey organization as an attachment to the issued technical assignment. Other materials that characterize the natural conditions of the projected construction area and are at the disposal of the design organization are also subject to transfer.
The terms of reference are drawn up according to the form below with text and graphic applications.
In paragraph 7 of the task, the following technical characteristics must be given: responsibility class, height, number of floors, dimensions in the plan and design features of the structure being designed; values of ultimate deformations of the foundations of structures; the presence and depth of basements; planned types, dimensions and depth of foundations; nature and values of loads on foundations; features of technological processes (for industrial construction); building density (for urban and settlement construction). In many cases, it is advisable to give these characteristics in the appendix to the terms of reference in tabular form. The terms of reference must be accompanied by: situational plans indicating the location (location options) of construction sites (sites) and utility lines; topographic plans on a scale of 1: 10,000-1: 5,000 indicating the contours of the location of the designed buildings and structures and engineering communications routes, as well as planning marks; copies of protocols for approval of passages and connections (connections) of engineering communications that affect the composition and scope of engineering surveys, with graphic applications; materials of executive surveys or design documentation of underground utilities (during the production of surveys at the sites of existing industrial enterprises and within urban areas).
The terms of reference is the basis for drawing up a survey organization
Her research program, which substantiates the stages, composition, volumes, methods and sequence of work and on the basis of which an estimate and contractual documentation is drawn up. The compilation of the program is preceded by the collection, analysis and generalization of materials on the natural conditions of the survey area, and, if necessary (absence or inconsistency of materials), a field survey of the survey area.
The program includes a text part and applications. The text part should consist of the following sections: 1) general information; 2) characteristics of the survey area; 3) knowledge of the survey area; 4) composition, scope and methodology of surveys; 5) organization of work; 6) list of submitted materials; 7) list of references.
Section 1 provides the data of the first five points of the terms of reference. Section 2 gives a brief physical and geographical description of the survey area and local natural conditions, reflecting the features of the relief and climate, information about the geological structure, hydrogeological conditions, adverse physical and geological processes and phenomena, the composition, condition and properties of soils. Section 3 provides information about the available stock materials of previously performed survey, search and research work and assesses the completeness, reliability and degree of suitability of these materials. In Section 4, based on the requirements of the terms of reference, the characteristics of the area (site) of the survey and its knowledge, the optimal scope and scope of work are determined, and the choice of methods for conducting engineering and geological research is justified. When agreeing on the program, designers should pay special attention to this section, guided by the information on the composition and scope of work given below in paragraphs. 2.3 and 2.4. Section 5 establishes
the sequence and planned duration of work, the necessary resources and organizational measures, as well as environmental protection measures are determined. Section 6 indicates the organizations to which the materials should be sent, as well as the name of the materials. Section 7 provides a list of all-Union regulatory documents and state standards, industry and departmental instructions (instructions), guidelines and recommendations, literature sources, survey reports that should be used in the production of surveys.
The survey program must be accompanied by: a copy of the customer's technical specifications; materials characterizing the composition, volume and quality of previously performed surveys; plan or diagram of the object indicating the boundaries of the survey; a project for the location of points of mine workings, field research, etc., made on a topographic basis; technological map of the work sequence; drawings (sketches) of workings and non-standard equipment.
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