A semi-analytical framework for one-dimensional collapse analysis of partly saturated soils

Despite the increasing interest to understand the behavior of collapsible soils, a very limited number of procedures have been proposed to perform analyses in order to predict collapse settlements. Hence, simple models that would enable engineers to undertake analyses within the one-dimensional and two-dimensional frames are still desirable. The present paper proposes an efficient semi-analytical framework where it is shown that collapse settlements can be estimated with a very reasonable computational effort. A semi-analytical procedure is developed within a one-dimensional framework and can be extended to two-dimensional and three-dimensional problems. In this procedure, the analytical solution of the infiltration problem is combined to a collapse model in a semi-analytical process where the soil layer and time period are divided into regular increments. Each increment over the soil layer depth is considered as a small soil element for which parameters such as moisture content and pressure head are estimated as functions of time. Local volumetric strain caused by soil collapse is estimated using a collapse model and integrated numerically to find the total settlement. The soil collapse settlement can be analyzed in conjunction with volumetric moisture content. Effects of parameters such as permeability and collapse modulus can be analyzed as will be shown.