Elastic-plastic Solution for Undrained Expansion of Cylindrical Cavity in Saturated Structured Loess

Abstract:

To derive a rigorous solution for undrained expansion of cylindrical cavity， the modified Cam-clay model of structured loess was employed to describe the mechanical properties of loess. The small deformation assumption was used to solve the soil stress and deformation in the elastic zone around the cavity. Besides， the boundary value problem of cylindrical cavity expansion can be transformed into three first-order nonlinear ordinary differential equations with the stress component as the basic unknown quantity in the plastic region. The governing equation was solved by using the stress component on the elasto-plastic interface as the initial condition to obtain the stress distribution in the plastic zone around the cavity， then the pore water pressure was derived by integrating the radial equilibrium equation. The correctness of the method in this paper is verified by parameter analysis. The results show that the degenerate solution is completely consistent with the existing numerical solution， and the soil structure has a significant effect on the stress component， the specific volume， the excess pore water pressure， and elastic-plastic radius.