Estimation of Undrained Shear Strength of Overconsolidated Clay Using a Maximum Excess Pore Pressure Method Based on Piezocone Penetration Test (CPTU)

Many methods can be used to evaluate the undrained shear strength (s(u)) in unconsolidated or normally consolidated clay. However, among the many methods, few methods can be used to evaluate the su value in overconsolidated clay. In this paper, based on the piezocone penetration test (CPTU), the maximum excess pore pressure method (Delta u(max)) was adopted to estimate the s(u) in overconsolidated clay. In addition, three different test sites (in China) with overconsolidated clays were selected to verify the feasibility of this method. The test results show that the maximum pore pressure cone factor (N-Delta umax) significantly affected the evaluation of su. Moreover, the N-Delta umax values (8.10, 8.70, and 8.44) for 3 test sites in Yancheng, Nanjing, and Changzhou were obtained and can provide a valuable reference for evaluating s(u) for in situ tests with overconsolidated clay.