Undrained cavity expansion in modified Cam clay I: Theoretical analysis

This paper presents an analysis of the undrained expansion of a cavity in modified Cam clay. The problem is formulated in small strain in the elastic zone and large strain in the plastic zone. Exact closed-form solutions of the effective stresses around the expanded cavity are presented. Closed-form expressions for the excess pore water pressure and the total stresses have also been derived based on a simplified assumption regarding the shear stress variation around the cavity. The analytical solution shows clearly the influence of the overconsolidation ratio on the excess pore water pressure induced by cavity expansion. As both the excess pore water pressure and the cavity pressure are expressed explicitly in terms of the primitive modified Cam clay parameters, the solutions may provide a theoretical basis for the interpretation of in-situ tests such as the piezocone test and the pressuremeter test.