Post-Liquefaction Settlement Reduction Due to Vertical Reinforcement of Aggregate Piers-PPT Presentation

PPT Presentation

Pdf Summary

This study examines how aggregate piers reduce post-liquefaction settlement in deep liquefiable soil layers through axial reinforcement. Conventional free-field methods estimate volumetric settlement but do not account for reinforcement, potentially producing conservative predictions.<br /><br />The researchers used Gingery’s (2019) post-liquefaction constitutive model in axisymmetric FLAC unit-cell simulations. The model represents settlement during excess pore-pressure dissipation through changes in soil constrained modulus. Simulations compared improved and unimproved ground, including cases that isolated the piers’ axial reinforcing effect from other benefits such as soil densification and reduced pore-pressure generation.<br /><br />The modeling approach was assessed against centrifuge tests by Adalier et al. (2003) and blast-induced liquefaction field tests by Amoroso et al. (2020). The simulations showed reasonable agreement with the test results. They also indicated that downdrag transfers stress to the aggregate piers, helping reduce settlement.<br /><br />Across the modeled cases, considering axial reinforcement alone reduced settlement by approximately 18% to 26%. The findings suggest that accounting for aggregate-pier reinforcement can improve estimates of post-liquefaction settlement compared with free-field calculations.

Keywords

aggregate piers

post-liquefaction settlement

liquefiable soil

axial reinforcement

free-field methods

Gingery model

FLAC simulations

excess pore pressure dissipation

centrifuge tests

downdrag stress transfer