A Series of Centrifuge Experiments Investigating the Effect of High Confining Pressure on Sand Liquefaction

This paper introduces a series of centrifuge tests - under low and high confining pressures - designed to study the effect of effective overburden pressure on liquefaction potential of clean sand. All the centrifuge tests simulate about 5 m saturated clean sand deposit under effective overburden pressure of 1 and 6 atm with relative density ranging from 45% to 80%. To achieve the targeted overburden pressures, a dry layer of lead shots with different thickness was deposited on top of the clean sand. Viscous fluid was used for saturation to keep constant prototype permeability. All the centrifuge tests were subjected to 10-cycle sinusoidal seismic motions with different prototype peak acceleration to achieve the targeted maximum excess pore pressure buildup. Acceleration, pore pressure build-up and dissipation, and shear wave velocity were monitored, recorded, and analyzed during or after shaking. Acceleration amplification was observed in experiments conducted under low confining pressures, while de-amplification was found in experiments conducted under high confining pressures.