A practical lateral spreading pressure model for piles in inclined liquefied ground

Liquefaction-induced lateral spreading is a main cause of pile failure during earthquakes because it places considerable soil pressure on piles. The lateral spreading pressure originates not only from liquefied soil but also from nonliquefied soil when it overlays a liquefied soil layer. In this study, we develop a practical lateral spreading pressure model for pseudostatic analysis to analyze pile response in inclined liquefied ground. The model comprises two parts. First, using a laminar flow model, the lateral spreading pressure of liquefied soil is modeled as the equivalent fluid flowing pressure. The coefficient of viscosity of the liquefied soil is constructed on the basis of shaking table tests in the literature. The normalized lateral spreading pressure depends on the liquefied soil thickness-to-pile diameter ratio. Second, for nonliquefied soil, individual p-y curves for uphill and downhill soils are used to simulate their distinctive soil reaction mechanisms. The uphill soil is subjected to lateral spreading soil displacement, whereas the downhill soil is subjected to pile displacement. This approach can elucidate the net soil reactions of the downhill and uphill soils that vary depending on pile stiffness. The proposed model is validated through simulations involving 1-g shaking table tests, centrifuge tests, and case histories reported in the literature.