A constitutive model of unsaturated expansive soils considering influences of capillary and adsorptive components of matric suction

Abstract

Contrary to classic plasticity, the BSP theory introduces a non-zero plastic strain rate even inside the Bounding surface (analogous but not identical to the classic Yield Surface), with its amplitude increasing as the current stress point approaches the Bounding Surface. This is achieved by making the plastic modulus to depend on the distance δ between the current stress point σ ′ and an arbitrarily defined image stress point σ ′ located on the Bounding Surface (Fig. 1). This definition leads to a smoothing of the stress-strain curve from small to large strains, reproducing more realistically experimental observations. It exists different ways to define the image stress σ ′ , the method called “radial mapping”, being the simplest and the most widely used, is adopted here. It consists of extrapolating the position vector linking the origin to the current stress until it intersects the image stress on the bounding surface, as illustrated in Figure 1.