Effect of Deformation-Induced Suction in the Behavior of Unsaturated Fine-Grained Soils Using Simplified Finite-Element Model

Abstract

Matric suction is one of the important variables used to characterize the deformation behavior of unsaturated soil. The stress-strain relationship and the governing differential equations are the two elements in which suction is incorporated in the development of mathematical models for the dynamics of unsaturated soils. In this paper, a simplified finite-element model was used to understand the effect of initial suction and deformation-induced suction variation in the static and dynamic behavior of silty and clayey soils. The simplified finite-element model was developed by neglecting the relative acceleration and velocity terms associated with water and air phases in the fully coupled governing differential equations. The stress-strain behavior of the solid skeleton was represented by linear elastic model, a simple model to explain the computed responses using basic theory. The suction-degree of saturation relationship was modeled by the Brooks and Corey model. Simulation results showed that the initial degree of saturation has significant influence on the behavior of clayey soil compared with silty soil. It is also observed that the effect of matric suction in the Bishop’s effective stress equation is significant if the clay and silt are relatively soft.