Experimental and Numerical Modelling of Spudcan Penetration in Stiff Clay Overlying Soft Clay

Abstract

Spudcan penetration in stiff clay overlying soft clay, herein referred to as two-layer clay, carries the risk of rapid spudcan penetration or `punch-through?. In the present study, centrifuge tests of spudcan penetration in two-layer clay are conducted to measure the load-penetration response as well as to observe the soil failure mechanisms during the penetration. To enable comprehensive parametric studies, numerical analysis of spudcan penetration in two-layer clay is conducted using Eulerian finite element method. The measured load-penetration response is shown to change from a `post-peak reduction? profile to a `monotonic increase? profile with decreasing crust layer thickness. The numerical analysis shows that a strain-softening crust that is `brittle enough? may be simply approximated by an equivalent non-softening crust with strength equal to the softened (or residual) strength. Finally, a design method for estimating spudcan load-penetration response in two-layer clay is proposed and compared with existing experimental and field data.