Optimization of Vibrocompaction Design for Liquefaction Mitigation of Gravity Caisson Quay Walls

Abstract

Gravity-type caisson walls are a type of popular but easily damaged waterfront construction structure, especially in seismic regions. Various forms of mitigation have been successfully applied to improve their performance when subjected to liquefaction. Establishment of an effective, reliable, and easily implemented liquefaction remedial design procedure based on commonly used ground improvement technology is important. In this study, following the philosophy of performance-based design, a novel optimization process was developed and applied to a well-known case study. The vibrocompaction method was examined within a framework of a well-calibrated case history to hypothetically improve the seismic performance of a damaged caisson quay wall to an acceptable level. This study includes three major steps: first, the constitutive model used in this study for describing liquefaction was calibrated based on the published data; second, a caisson quay wall case history damaged by liquefaction was simulated as the unimproved benchmark; finally, the vibrocompaction method was applied as the mitigation technique to provide improvement to an acceptable level, and the mitigation design was optimized. The remedial program design characteristics, such as improved soil zone lateral extent in backfill soils and improved zone depth in foundation soils, were optimized. Through a parametric study, insights and recommendations on the establishment of liquefaction remediation design and optimization process for gravity-type caisson wall are provided for further study.