Mechanics of Unsaturated Soils for the Design of Foundation Structures

Design of foundations for unsaturated soils is based on conventional soil mechanics assuming saturated conditions for soils. In this paper, semi-empirical models for predicting variation of the bearing capacity and the modulus of elasticity with respect to matric suction for unsaturated soils are presented. The saturated soil properties (i.e. bearing capacity and modulus of elasticity) and the Soil-Water Characteristic Curve (i.e. SWCC) are required for using these models. In addition, a simple method is also detailed to estimate matric suction of as-compacted soils using a pocket penetrometer. The proposed techniques are simple and should encourage geotechnical engineers to implement the mechanics of unsaturated soils into practice.