Undrained solution of cylindrical cavity expansion for unsaturated soils with modified Cam-clay model

This paper develops a new semi-analytical approach for undrained cylindrical cavity expansions in unsaturated soils. The soil behavior is described within simple, yet effective, critical state-based elastoplastic framework with suction being treated as hardening parameter. Different from its saturated counterpart, the expansion problem soils involves five basic variables, namely, three stress components, specific volume, and suction. A constitutive equation water phase, addition to relationship plus radial equilibrium condition, therefore required construct set of coupled, self-contained differential equations solution boundary value problem. With introduction an auxiliary variable, all these governing can be expressed terms Lagrangian formulation then simultaneously solved through standard numerical procedure. example results show that has significant effects on overall responses and, particular, trajectories calculated representative element at surface. It also interesting observe shear dilation phenomenon, developed during course expansion, usually occurs relatively dense high