Analysis of Laterally Loaded Piles in Liquefiable Soils with a Frozen Crust Using P-y Approach

Liquefaction has been commonly observed in past major earthquakes across the world and has caused extensive damages to the built infrastructure. A substantial portion of these ground failures and structural damages was direct results of or related to lateral spread. Lateral spread is particularly damaging if a non-liquefiable crust rides on top of the liquefied soil. When the ground crust is frozen, its physical properties including stiffness, shear strength and permeability will change substantially. What would be the impact to a bridge pile foundation if there is a frozen ground crust that is resting on top of the liquefied soil? This paper reports preliminary results by using the simplified static beam on nonlinear Winkler foundation (BNWF) approach. A p-y curve for frozen silts was used to model the frozen crust-pile foundation interaction and assess the pile response under lateral spreading and inertial load. Lateral spread was modeled by imposing free-field soil displacements. The pile responses including bending moment and shear force predicted by the BNWF approach agree well with those from the fully coupled 3D FE model reported in a separate paper. It is tentatively concluded that the BNWF approach can be used to predict the pile performance in the seismic design of deep foundations embedded in liquefiable soils in the cold regions.