Seismic analysis of pile in liquefiable soil and plastic hinge

Abstract

Liquefaction is one of the leading seismic actions that cause extensive damage to buildings and infrastructure during earthquakes. In many historic cases, plastic hinge formations in piles were observed at inexplicable locations. This project investigated the behaviour of piled foundations within soils susceptible to liquefaction by using numerical analysis carried out in Abaqus software in terms of plastic hinge development. Three different soil profiles were considered in this project that varied in the thickness of both the liquefiable and non-liquefiable layers, pile length and free-and fixed-head pile conditions. Modelling a single pile as a beam-column element carrying both axial and El Centro record earthquake loading produced results of the seismic behaviour of piles that could be assessed by force-based seismic design approaches. The displacements and deformations induced by dynamic loads were analysed for piles affected by liquefaction, and the results were used to demonstrate the pile capacity and discuss the damage patterns and location of plastic hinges. Parametric studies generally demonstrate that plastic hinge formation occurs at the boundaries of the liquefiable and non-liquefiable layers; however, the location can be affected by a variety of factors such as material properties, pile length and thickness of the liquefied soil layer.

Comparative Analysis of Performance of Mat Foundations in Non-liquefiable and Liquefiable Soil

“…Table 1 provides foundation soil parameters from two studies: (Kang & Jie, 2017) and (Rostami et al, 2017) and were utilized in the finite element analyses. For non-liquefiable soil, parameters are derived from both studies, whereas liquefiable soil parameters are based solely on Rostami et al (2017).…”

“…Table 1 provides foundation soil parameters from two studies: (Kang & Jie, 2017) and (Rostami et al, 2017) and were utilized in the finite element analyses. For non-liquefiable soil, parameters are derived from both studies, whereas liquefiable soil parameters are based solely on Rostami et al (2017). Note that all these soil properties have different parameters, for instance, the nonliquefiable soil (NLS) layer of medium-dense silty sand (MDSS) is different from the liquefiable soil (LS) layer of MDSS.…”

“…In this study, a distinct 3D model of soil configuration surrounding the footing was examined, with a homogenous thickness of the liquefied layer as well as material properties, to investigate how a footing performs in liquefaction events. Soil parameters, drawn from previous case studies (Rostami et al, 2017;Sarkar et al, 2014), were meticulously chosen to ensure the validity of the results. During liquefaction events, the pore water pressure within the liquefiable layer increases, resulting in a reduction of effective stress and a consequent decrease in shear strength.…”

The Dynamic Behaviour of Pile Foundations in Seismically Liquefiable Soils: Failure Mechanisms, Analysis, Re-Qualification

“…Ramirez et al [111] compared the predictive capabilities of PDMY02 and SANISAND platforms. Furthermore, Drucker-Prager [117] and Mohr-Coulomb plasticity [118] models are also soil constitutive modelling approaches in 3D analyses of soil-foundation systems.…”

“…It was reported that the plastic hinge length of piles extending through liquefiable layers is about 1.4 times larger than that of non-liquefiable conditions. However, the location of plastic hinges can be affected by a variety of factors, such as material properties, pile length and thickness of the liquefied soil layer [118]. Wang and Orense [125] used a 2DBNWF finite element model implemented via Open Sees to analyse the response of raked pile foundations in liquefying ground.…”