Estimation of Cone Factor in Undrained Clay Using Spherical and Cylindrical Cavity Expansions
Please login to view abstract download link
The current cone factor of piezocone penetration tests is derived based on the assumption of elastic perfectly-plastic soil, and the soil rigidity index in the formula is empirically determined. This study proposes a method for explaining cone penetration tests in clay based on the undrained cavity expansion solution assuming the nonlinear hardening model to describe the undrained behaviour of normally consolidated clay during spherical and cylindrical cavity expansions, respectively. The ALE (Arbitrary Lagrangian Eulerian) large deformation finite element method is used to analyse the influence of factors such as rigidity index, cone roughness, and failure criteria during the penetration process. The formula of the cone factor is then proposed and correlated with the ultimate expanding pressure of the spherical cavity, in which the rigidity index is determined based on the load-displacement curve of cylindrical cavity expansion. The rationality of the cone factor is verified by comparing with the ALE analysis results and those published studies. Experimental analysis is also conducted using a self-developed combined penetration and expansion measuring device, and the results show that the proposed method can reasonably predict the undrained strength of soft soils.