MODELING OF PHYSICAL-MECHANICAL PROPERTIES OF SAND-GRAVEL SOIL MIXTURES BY PFC-SOFTWARE

Abstract

The physical and mechanical properties of gravel and sandy soils, as well as mixtures made on their basis, must be considered from the standpoint of the theory of a discrete medium — as loose bodies. Recently, more and more scientists are attracted to the research of physical and mechanical properties of loose soils with the help of various mathematical programs created on the basis of discrete medium theory. The article is devoted of the problem of creating loose soils with given properties taking into account the theory of a discrete medium using the PFC software. It allows to simulate tests of loose soils on shear and to assess the effect of the grain size distribution on the magnitude of the angle of internal friction and the adhesion of test ground mixtures. PFC software is very relevant and effective when studying the physical and mechanical properties of ground mixtures. The technique of creation, research and modeling of mixtures of sandy and sandy-gravel soils with given physical and physical-mechanical properties is developed and justified, based on the application of the theory of discrete medium with the help of the PFC software. In accordance with this theory, the distribution of stresses in a dispersed system depends on its granulometric composition. It is established that the large particles that make up the skeleton of the soil mixture, when they compose more than 30% by weight, are most responsible for the formation of a stress field in the soil’s volume: the transfer of contact stresses within soil mixtures during shear or compacting by a uniformly distributed load occurs predominantly through large factions («skeletal» factions). When the mass content in the aggregate mixture is less than 30%, contacts between the particles are formed mainly by «skeletal» particles. If the mass content of the aggregate exceeds 30%, then contact stresses between adjacent fine particles develop gradually, as well as stresses between «skeletal» and smaller particles. At the same time, the strength of sand-gravel mixtures, estimated by the angle of internal friction, decreases and tends to the strength of the aggregate itself.