Liquefaction-induced large displacement of pile-supported wharf

Abstract

Centrifuge model tests were carried out to investigate the dynamic behaviour of a pile-supported wharf in front of backfilled gravity type caissons, focusing on the failure mechanism of the piles, the effects of liquefaction in the backfill and underlying sand layer on the permanent deformation of the wharf during earthquakes, and the dynamic interaction between the piled deck and caisson through the approach bridge. The targeted piled structure is the pile-supported wharf damaged in the 1995 Hyogo-ken Nambu Earthquake at Takahama, Kobe. Liquefaction of the foundation soil and the backfill behind the caisson during an earthquake-like shaking causes large seaward lateral movement of the rubble mound. As a result, a large horizontal displacement gap was formed between the rubble mound and the bearing stratum. This displacement gap caused a very large bending moment in the pile, at the pile top and in the bearing stratum just below the sand layer. These locations where large bending moments were observed agreed with the locations where large pile deformations were observed at the Kobe site. Centrifuge model tests reasonably predicted the failure mode of the piled wharf observed in the Kobe Earthquake. Varying the thickness of the sand layer under the rubble mound caused a change of the deformation mode of both ground and structures. The test without the sand layer showed no displacement gap between the rubble mound and the bearing stratum, resulting in small permanent displacement of the wharf, while a thicker liquefiable sand layer did not necessarily cause a larger deformation of soil and the structures.

Enhancing Seismic Capacity of Pile-Supported Wharves Using Yielding Dampers

“…As suggested by Takahashi and Takemura [25], one of the most important reported wharf damages was bending moment on piles due to their large lateral drifts. Therefore, in this example, drift of the middle pile is considered as the response of the structure and is compared in different cases.…”

Nonlinear static analysis of a pile-supported wharf

“…The region studied has high seismicity with an important liquefaction potential [9,18]. Liquefaction is the process by which the sediments immersed suffer a loss of resistance and stop behaving as a solid to become a viscous liquid.…”

Modal analysis of pile‐supported structures during seismic liquefaction

“…To minimise the reflection of P-waves from the endwalls as well as to aid the dissipation of energy, sheets of absorbing materials were placed on both endwalls of the container. The use of soft materials as remediation of the wave reflection has been already considered by previous researchers in both centrifuge [33,34] and shaking table tests [35].…”