Shearing Resistance of Soils as a Rate Process

An expression relating compressive resistance of soils to effective stresses, soil structure, rate of strain, temperature, and frictional and cohesive soil properties is derived using rate process theory, which is based on statistical mechanics concepts. The resulting expression reduces to a form analogous to the Coulomb equation, under conditions of constant structure, strain rate and temperature. Computation of the compressive resistance of hypothetical soils for which reasonable assumptions are made for unknown parameters yield results of the proper order of magnitude. Test data on the effects of rate of strain, temperature and structure show behavior in accord with the theory. It is demonstrated that the number of interparticle contacts per unit area of soil cross section is the most important single factor influencing cohesion, and it is shown why cohesion is only of importance in clay soils.