Peculiarities of using the hypothesis of S.O. Kulon for soil dispersed sediments

Abstract

The publication is devoted to the outstanding French scientist Charles Auguste Coulomb, who 250 years ago (1773) proposed a hypothesis that relates tangential and normal stresses through the angle of internal friction of soils. This hypothesis provides reliable results while maintaining Hooke's law. Beyond this law, it is necessary to take into account the property of the soil medium, namely the change in volume during shearing or displacement of soils, which requires the introduction of additional dilatancy parameters.
 It is known that there are two types of friction in nature: sliding and rolling friction. At certain values of deformation in the soil medium, sliding friction, which is characterised by the traditional value of the internal friction angle, initially appears in certain zones of the soil medium at low deformations. Further increase in deformation causes rolling friction, which is characterised by a different value of the internal friction angle, almost one third less than the traditional value of the internal friction angle of the soil. This fact must be taken into account when performing numerical modelling of a dispersed soil medium from the beginning of loading to its failure. In this publication, we discuss the methodology for finding the parameters of the dilatancy theory to reveal the elastic-plastic deformation of cohesionless soils based on experimental results. Recommendations are given on the use of the Coulomb hypothesis in engineering calculations and on the relationship between tangential and normal stresses through the angle of internal friction of soils. For a correct description of the nonlinear process of soil deformation, it is necessary to use the parameters of the dilatancy theory, which can be investigated on an axisymmetric shear tester.
 The results of tests of sand of medium size, medium density, low-moisture, homogeneous on several devices showed that the values of the angle of internal friction of soils differ depending on the design of the device. This fact is recommended to be taken into account when designing geotechnical facilities.