Crust Effects on Liquefaction Response: Insights from Centrifuge Tests

A series of seismic centrifuge tests were performed to investigate how the hydromechanical characteristics of non-liquefiable crusts influence the response of layered liquefiable deposits. Two vertically continuous liquefiable profiles were examined, each overlain by three contrasting crust types: dense coarse sand, lightly overconsolidated silt, and heavily overconsolidated clay. High excess pore pressures developed throughout the liquefiable profiles and sustained upward flow, with crust properties governing how this inflow was accommodated and discharged. In sand-crust models, substantial drainage occurred during shaking, reducing liquefaction severity in the underlying critical layer while enabling early co-seismic settlement. The low-permeability silt and clay crusts promoted fluid accumulation and prolonged liquefaction in the critical layer but produced contrasting surface responses. The silt combined sufficient hydraulic resistance to intensify void redistribution with insufficient mechanical and erosion resistance to maintain crust integrity under cyclic loading and subsequent seepage. Extensive fluidization of the critical layer and breakdown of the silt structure produced large settlement and surface ejecta. The clay largely retained its stiffness and structural integrity, partly decoupling surface movement from underlying sand sedimentation. The findings demonstrate that factors beyond crust thickness, including crust permeability, stiffness, cyclic strength and erodibility, strongly influence liquefaction response and related damage potential.