Influence of ground motion characteristics (velocity pulse and duration) on the pile responses in liquefiable soil deposits

Abstract

In this paper, three-dimensional finite-element analyses are conducted to study the effects of ground-motion duration and the presence of velocity pulse on the pile responses in liquefiable soils. The soil-pile system consisting of liquefiable granular deposits and rigid piles is modeled in OpenSeesPL. Four suites of ground motions, namely one pulse-like, one non-pulse-like, one long-duration, and one short-duration suite, are appropriately selected from worldwide earthquake events. Dynamic analyses are conducted for the soil-pile system under the excitations of four selected ground-motion suites. It is indicated that the pulse-containing ground motions bring in greater pile-bearing bending moments and shear forces as compared to the non-pulse-like suite, with the increase ratios of the mean peak bending-moments and shear-forces up to 27% and 34%, respectively. Furthermore, as compared to the short-duration suite, using the long-duration ground motions yields similar pile responses (bending moments and shear forces) but a substantial increase of the pile's permanent lateral displacements. The mean lateral displacements at pile head are 0.62 m and 0.17 m under the excitations of the long- and short-duration suites, respectively. In addition, correlation analyses indicate that peak ground velocity and Arias intensity can be regarded as effective intensity measures to evaluate the pile response (e.g., bending moment) and lateral displacement for a pile-reinforced liquefiable ground system. The results could provide useful insights for applying the pile-pinning approach in areas where pulse-like or long-duration ground motions are of the main concern.