Centrifuge test determination of wharf responses due to spatially and temporally varying interactions between wharf piles and liquefied soil

Abstract

Damage to wharf piles in liquefied soil has been observed in many strong earthquakes. A good understanding of soil-pile interactions is essential. Most previous studies ignored the variation in the interactions between piles and interpile soil. In addition, for wharves, the interactions vary with the development of pore water pressure under waterfront conditions. In this work, a centrifuge test was used to analyse the wharf response to soil-pile interactions, including spatial location and temporal characteristics of the wharf response. To investigate the varying shear resistance considering spatiality and time, the soil shear stress and strain at different vertical and lateral locations were divided into phases depending on the development of pore water pressure. Soil acceleration in the time and frequency domains, accompanied by pore water pressure accumulation, was examined. The response of the pile and deck, which varies in accordance with the soil behaviour, has also been systematically investigated. The impact of nonuniform soil liquefaction on pile-soil interactions was examined. The results show that the deformation of interpile soil was impeded by piles, resulting in alternating shear contraction to dilation after rapid accumulation of pore water pressure. This phenomenon decreases the acceleration amplitude of interpile soil in the time domain and frequency domain. The frequency bandwidth of the soil response was narrowed by pore water pressure build-up, and it was also affected by the extent of liquefaction. Amplification is produced in shallow-depth soil because the bandwidth overlaps the predominant bandwidth of the soil response. Significant changes in the soil shear response induce pronounced variations in the pile response.