Simple Approaches for the Design of Shallow and Deep Foundations for Unsaturated Soils II: Numerical Techniques

Numerical techniques are widely used in conventional engineering practice for obtaining the stress versus settlement or load versus displacement (P–δ) behavior, respectively, and use the information in the design of shallow and deep foundations, extending the principles of saturated soil mechanics. This Companion Paper II summarizes the details of numerical techniques that can be used in the design of shallow and deep foundations in unsaturated soils. The two key properties required for performing the numerical techniques are the shear strength and the modulus of elasticity of unsaturated soils. A user-friendly subroutine (USDFLD) has been developed for use in the commercial software, ABAQUS to predict the variation of these soil properties with respect to matric suction. The only additional information required for performing the numerical modeling in addition to the conventional soil properties is the soil–water characteristic curve. Good agreements were observed between the proposed numerical techniques and from theoretical approaches and experimental studies. The numerical techniques discussed in this paper are simple and can be used by the geotechnical engineers in the design of shallow and pile foundations in unsaturated soils.