A semi-analytical solution for displacement-controlled elliptical cavity expansion in undrained MCC soil

Conventional cavity expansion theory is a one-dimensional problem and is not applicable for the two-dimensional cavity expansion issue, which is also required for geotechnical problems. This paper proposes a novel semi-analytical solution for displacement-controlled elliptical cavity expansion (DC-ECE) in undrained soil. The displacement and strain fields for DC-ECE are obtained from the strain path method (SPM) with the aid of conformal mapping theory. The effective stress can be subsequently obtained by the incremental stress-strain calculation using a suitable constitutive model such as the MCC model. Then, the computed effective stress results are substituted into the stress equilibrium equation to give the pore pressure solution. The new semi-analytical solution reveals the non-axisymmetric characteristics of DC-ECE and allows the elastic-plastic (EP) boundary, excess pore pressure, stress, and displacement to be calculated. The proposed method provides a solution to non-axisymmetric cavity expansion issues and it can be applied to geotechnical engineering problems, including vertical drain installation, flat dilatometer tests and noncylindrical pile penetration in clay.