On the Need to Adjust Standards for Designing Soil Bases of

Buildings and Structures from the Standpoint of Real Soil

Deformation

A. N. Alekhin

Ural State University of Railway Transport, Ekaterinburg, Russia

Keywords: Soil base of structures, soil, deformation, physical nonlinearity, mathematical model, model parameters,

determination of parameters.

Abstract: The article substantiates the need to adjust standards for geotechnical designing on the base of nonlinear soil

mechanics adequate to real soil deformation. Nowday all main regulatory documents for geotechnical design

contains outdated formulas for calculation of soil base deformations on the base of Hooke’s linear theory

(model) designed for metals and other, so-called, constructive materials with strong and dense internal bonds.

Correction of this unnatural situation into direction of application in geotechnical design adequate to soil

nonlinear model is very important for ensuring safety and reliability of building and structures.

1 INTRODUCTION

Taking into account achievements of experimental

and theoretical geotechnics it seems necessary that

regulatory documents for design of soil bases of

foundations clearly indicate that when designing

foundations both on natural and artificial non-rock

soil (hereinafter referred as to soil) must be used only

adequate to soil, physically nonlinear models, main

feature of which is reflection of dependence of soil

stiffness (resistance to deformation) on its stress-

strain state (hereinafter referred as to SSS). However,

for now this is clearly indicated only at Federal Law

“On Safety of Buildings and Structures” (Federal

Low № 384-FZ, 2010), but design Code of Rules SP

22.13.330.2016 “Soil Bases of Buildings and

Structures” (Gosstroyizdat of Russia, 2017) contains

outdated provisions on calculation of soil base

deformations using formulas for linear deformable

materials with strong and dense ion-electronic,

cementation or polymer internal bonds inherent for

metals, concrete, natural stones (rock) and rubber

while non-rock soils have loose internal bonds in the

form of friction and cohesion, on which was

definitely pointed out in 1925 year founder of

International Geotechnical Society Terzaghi

(Tеrzаghi, 1925). Such an extraordinary

contradiction in main regulatory documents on

geotechnical design and not only in them, but also in

State Standards for determining soil deformation

characteristics (GOST 20276-2012, 2013) has

developed since 1950s due to a lack of information

about real features of soil deformation and complete

absence of technical means for complex geotechnical

calculations. In fact, data on real physically nonlinear

soil deformation were obtained by soviet scientist

Botkin as early as 1939…1940 with using new

german triaxial device for studying non-rock soils

deformations – stabilometer (Botkin, 1939; Botkin,

1940).

But war in USSR in 1941…1945 did not allow

to complete these investigations and problems of

speed restoration of destroyed structures after the

war, that required accelerated development of

regulatory documents for building created a situation

in which it was necessary to accept Terzaghi’s

proposal of 1925…1943 years (Tеrzаghi, 1925;

Tеrzаghi, 1961) on using during some period of time

for calculation of soil deformation the theory of

deformation of the simplest material in this respect –

steel, namely Hooke-Young linear theory with

stiffness E used in it and for metals, concrete and also

for all, so called, structural materials, usually called

Hooke’s modulus of elasticity or Young’s modulus of

physically linear deformation or most often simply

Young’s modulus, and for soils from 1940s at

incompletely correct suggestion of Gersevanov’

suggestion (Gersevanov, 1948) – modulus of

deformation (secant or tangent, in principle it does not

Alekhin, A.

On the Need to Adjust Standards for Designing Soil Bases of Buildings and Structures from the Standpoint of Real Soil Deformation.

DOI: 10.5220/0011582200003527

In Proceedings of the 1st International Scientiﬁc and Practical Conference on Transport: Logistics, Construction, Maintenance, Management (TLC2M 2022), pages 235-238

ISBN: 978-989-758-606-4

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

235

matter). Moreover, and type of deformation (elastic,

plastic, or their combination) is also not principle in

this case because in formulas for soil deformations,

obtained within framework of this linear theory,

deformation modulus E has physical and

mathematical meaning of proportionality factor

between stress σ and relative deformation ε, and

therefore it completely coincides with physical and

mathematical meaning of Young’s stiffness

characteristic E.

But according to numerous

experimental data starting from Hooke’s experiments

in 1640…1670 years with metal wires and springs

(Hooke, 1678), as well as subsequent studies with

other materials (Bell, 1984) the theory (model) of

physically linear deformation adequately reflects

deformations of materials with artificially created (by

melting, hydration, firing, polymerization or

vulcanizing) strong and dense internal bonds, for

example, in metals, concretes, ceramics or rubber;

same internal bonds with similar intensive, but

natural influences arose in natural stones (rocky

soils). On contrary in non-rock soils internal natural

bonds in form of friction and cohesion are rather weak

and chaotic, that determines a much more complex

nature of soil deformation compered to deformation

of metals or rubber. In the case of soils it is more

convenient to use more fundamental than Young’s

modulus E and later identified Poisson’s ratio ν,

stiffness characteristics, namely bulk modulus K and

shear modulus G: it turned out that for dense

structural materials classical (earlier) stiffness values

E and ν are determined simpler and more reliably, but

for soil such values are more fundamental K and G.

Since both pairs reflect the same physical

phenomenon, namely mechanical deformation, there

is one-to-one correspondence between these pairs: E

= 3KG/(K+G); ν =0,5(K-2G)/(K+G); K = E/ (1-2ν);

G = 0,5E/(1+ν). These relationships are derived from

decomposition of total strain into volume and shape

change with corresponding decomposition of total

stresses. As a result, it is possible through generalized

parameters of these components of stress-strain state

(invariants of stress and strain tensors) to illustrate in

Fig.1 and Fig.2 fundamental difference between type

of structural materials deformation (physically linear

deformation) and type of non-rock soils (sands and

clays) deformation (physically nonlinear

deformation):

Results of actual tests of specific materials and

soils, schematically depicted in Fig.1and Fig.2 are the

basis for derivation of so-called determining physical

relationships between stresses and relative strains,

supplementing general Henki’s relations between

stresses and relative strains, which in turn are

included together with Newton’s equilibrium

equations, geometric Cauchy’s relations between

relative deformations and displacements, as well as

boundary and (or) initial by time conditions in general

system of resolving relations of any mechanical

problem (Hooke, 1678), including geotechnical

problems. For structural materials determining

physical relationships according to data of numerous

investigations (Bell, 1984) and to figure 1 usually

Figure 1: Physically linear deformation of structural

(metals, concretes, ceramics, plastics, rubber) materials

and rocks (K = const, G = const): ε - invariant of volume

part of total relative strain; ε

– invariant of form change

of total relative strain; σ , MPA and σ

, MPA – stress

invariants corresponding to these parts of total relative

strain; K – bulk modulus, MPA; G – modulus of shape

change modulus – shear modulus, MPA.

Figure 2: Physically nonlinear deformation of non-rock

(sands and clays) soils (K ≠ const, G ≠ const) :

designations are the same as in Figure 1.

TLC2M 2022 - INTERNATIONAL SCIENTIFIC AND PRACTICAL CONFERENCE TLC2M TRANSPORT: LOGISTICS,

CONSTRUCTION, MAINTENANCE, MANAGEMENT

236

have a very simple form: K = const; G = const and

therefore E = const and ν = const. This type of

deformation with constant coefficients between

parameters (values) of various kinds of deformations

and parameters (values) of various kinds of force

actions is called physically linear. But for soils

according to Botkin’s studies (Botkin, 1939; Botkin,

1940) and subsequent similar studies (Lomize, 1959;

Kopeikin, 1977) as well as to figure 2 even optimal

kind of determining physical relationships have much

more complex form than in the case of physical

linearity: for bulk modulus K = σ/ε = σ1-∝/A0 ≠

const and for shear modulus G = σI /εI = (σu - σi) /B

= (Aσ+C) / (B+εi) ≠ const (Here σu = Aσ + C –

strength condition for non-rocky soils according to

Mises and Botkin (Mises, 1928; Botkin, 1940); σ, σi,

ε, εi – parameters-invariants of SSS; A, B, C, A0, α

–constants of determining physical relationships. The

presence in determining physical relationships with

constants of variable parameters ov SSS determines

complex type of deformation with changing during

loading ratio between parameters (values) of various

types of deformations and parameters (values) of

various types of force effects, and therefore having,

according to figure 2 curvilinear graphical form of

these relationships. Of course, substitution in design

of complex real nonlinear) deformation of soil base

with SSS-dependent stiffness by an extremely

simplified nominal for soil linear deformation with

constant stiffness is dangerous with serious

deformations or even collapses, an example of which

due to such miscalculation is shown at Fig. 3.

Figure 3: Collapse of industrial building due yo incorrect

prediction of column foundations settlements.

Nowday it is clear that to ensure safety and

reliability of objects they must be designed taking

into account actual physically nonlinear deformation

of soil base – the supporting bearing element of the

structure. But in addition to complex type of soil base

deformation, which is different with materials

deformation, soil has another important feature –

natural origin with complex formed over a long

geological period its structure and stress affecting

stiffness. In USSSR application of physically

nonlinear soil model for geotechnical design began to

study since 1959 year (Lomize, 1959; Kopeikin,

1977), implemented in adoption in 1985 in SNiP

2.02.01-85 * (Ministry of Regional Development of

Russia, 2017), and then in the Federal Law № 384-FZ

(Article 16) (Federal Low № 384-FZ, 2010) and in SP

22.13330.2016 (paragraphs 5.1.11, 5.1.12, 5.3.3)

(Gosstroyizdat of Russia, 2017) the requirements to

use of a physically and geometrically nonlinear soil

model in geotechnical design. At the same time,

firstly, physically linear model (Hooke-Jung model)

is not mentioned at all in the Federal Law, and in SP

22.13330.2016 the formulas corresponding to it

remained as a relic due to the unpreparedness of

designers, builders and engineers - geologists. But

such a situation, as noted above, confuses designers,

which often leads to serious accidents. To resolve this

contradiction, it is necessary to concentrate in a

separate Appendix all points of SP 22.13330.2016,

reflecting the provisions of the theory of linear

deformation (the theory of a linearly deformable

medium) with a warning that they do not comply with

the requirements of paragraph 5.11 of this SP

(Gosstroyizdat of Russia, 2017) and Federal Law No.

384-FZ (Technical Regulations on the Safety of

Buildings and Structures) (Federal Low № 384-FZ,

2010).At the same time, it is necessary to indicate in

a separate Appendix, with subsequent addition,

physically nonlinear soil models that meet the

requirement of paragraph 5.1.12 (Gosstroyizdat of

Russia, 2017) on verification of the model, indicating

soil parameters necessary for determining and

methods for their determination( laboratory or in-situ

tests). It is necessary to determine real values of

parameters A, B, C, A0, α from results of in-situ static

tests with the simplest scheme and least disturbing

natural state of soil: at present only pressure meter

and bearing circle plate are such tests (Alekhin,

1982).

REFERENCES

Federal Low of 30.12.2009 № 384-FZ “Technical

Regulation on Safety of Buildings and Structures”. –

M.: Collection of Legislation of Russian Federation,

2010.

On the Need to Adjust Standards for Designing Soil Bases of Buildings and Structures from the Standpoint of Real Soil Deformation

237

SR (Set of Rules 22.13330.2016. “Soil Bases of Buildings

and Structures”. – Gosstroyizdat of Russia, 2017. – 224

Tеrzаghi, К., 1925. Erdbaumechanik auf

bodenphysikalischer Grundlage, p. 392.

GOST 20276-2012. Soils. Methods for in-situ

determination of strength and deformability

characteristics. – M.: Standartinform, 2013. – 50 p.

Botkin, A. I., 1939. Investigation of stress state at

cohesionless and cohesive soils. Proceedings of RIIG.

24, pp.153-172.

Botkin, A. I., 1940. On strength of loose and brittle

materials. News of VNIIG. 26, pp. 205-236.

Tеrzаghi, К., 1961. Theory of soil mechanics, p. 507.

Gersevanov, N. M., Polshin, D. E., 1948. Theoretical basis

of soil mechanics and their practical application.

Hooke, R., 1678. Lectures «De Potentia Restitutiva», or of

Spring: Explaining the Power of Springing Bodies.

Bell, J. F., 1984. Experimental Basis of Mechanics of

deformable solids. Part I. Small deformations. p. 596.

Lomize, G. M., Kryzhanovskiy, E. L., Vorontsov, E. I.,

1959. Investigation of regularities of deformability and

strength of soils under three-dimensional stress state.

Proceedings for VIII International Congress on Soil

Mechanics and Foundation Engineering, pp. 32-41.

Kopeikin, V. S., Solomin, V. I., 1977. Calculation of sand

base using physically and geometrically nonlinear

equations. Soil bases, foundations, and soil mechanics,

1, pp. 30-32.

Mises, R., 1928. Mechanik der plastischen Formänderung

von Kristallen. Zeitschrift für angewandte Mathematik

und Mechanik 8, 3.

SNiP 2-02-01-83*. Ministry of Regional Development of

Russia, 2017, p. 228.

Alekhin, A. N., 1982. Non-linear analysis of stress-strain

state of soil mass under static loading: Thesis of cand.

techn. degree, Urals politech. Institute, Sverdlovsk, p.

186.

TLC2M 2022 - INTERNATIONAL SCIENTIFIC AND PRACTICAL CONFERENCE TLC2M TRANSPORT: LOGISTICS,

CONSTRUCTION, MAINTENANCE, MANAGEMENT

238