Seabed is often consisted of layered soils with thin sand layer overlying soft clay which would result in an unexpectedly sudden and rapid penetration of spudcan foundation. The soil properties are often spatially varied which is hard to be simulated. The spatial variability of soils coupling with the large deformation in it render the prediction of the sudden failure very difficult. In this study, the random field theory was combined with the Coupled Eulerian-Lagrangian (CEL) method to investigate the large displacement problem of the spudcan penetrating in thin sand overlying soft clay considering the variability of soil strength. The penetration resistance and the failure surface of spudcan during the penetrating process were obtained and compared with that in the uniform soils. Meanwhile Monte Carlo simulations have been performed for 400 realizations of the soil random field and subsequent finite-element simulation of the deep penetration. The results show that punch-through failure occurs during the penetration. The mean peak penetration resistance decreases 6% when considering the spatial variability of the layered soils. The failure surface in the random soils are developed in the weaker region which is different from symmetrical failure surface in the uniform soils. Monte Carlo simulations demonstrate that 73% of the peak penetration resistance in the random soils are smaller than that in the uniform soils.
Lei Song, Tianlongyuan Qin and Jinhui Li
Keywords: spudcan foundation, large deformation, layered soil, spatial variability
Publisher: DFI