Design of Retaining Wall and Single Pile in Expansive Soils Using Unsaturated Soil Mechanics as a Tool

For retaining walls and pile foundations constructed in expansive soil area, mechanical behaviors of both these geo-structures are significantly influenced by the lateral swelling pressure (LSP) mobilized in the infiltration process. The currently used design methods for retaining walls and pile foundations are mostly based on saturated soil mechanics. Mechanical behavior changes with respect to water content or suction change are not given due consideration. A theoretical framework is developed for determining lateral earth pressure (LEP) behind the retaining wall and uplift friction along the single pile shaft in expansive soil using unsaturated soil mechanics. An example problem is illustrated to highlight the influence of LSP on a retaining wall and a single pile, constructed in typical expansive clay from Regina, Canada. The studies presented in this paper are useful to the practitioners who routinely design geo-structures such as the retaining walls and pile foundations in expansive soils.