Abstract: The current solutions to cylindrical cavity expansion cannot properly consider the mechanical properties of dense sand and overconsolidated soil. Therefore, there is some discrepency between the solution and the practical situation. In addition, there are few answers that can describe the expansion of undrained expansion in sand and clay uniformly. Based on the CSUH model, the elastoplastic matrix and the governing equations for undrained cylindrical cavity expansion are proposed. Based on the boundary conditions, the exact solutions to the governing equations are obtained numerically. The results show that the predicted results capture the stress−strain relationship more reasonably, including liquefaction, shear dilatancy, strain-hardening and softening, damping of dense state and overconsolidation ratio. Therefore, the proposed approach can reasonably simulate the variation laws of stress field and strain field during the expansion process in dense sand and overconsolidated soil.