1g-Shake table and numerical studies on mitigation of liquefaction induced uplift of underground structure

This study aims to develop a mitigation method to prevent liquefaction induced damages. Towards this, shake table tests are conducted on the scaled underground structure model buried in fully saturated sand bed subjected to sinusoidal input motion. The effectiveness of replacing the sand around the structure using permeable gravel is studied. The build-up of pore pressure and acceleration within the soil and the displacement of the structure are measured during excitation. The shake table results showed that the structure is subjected to liquefaction induced uplift upon shaking, and by using the replacement method, the uplift is reduced by 80%. A finite-difference analysis of the liquefaction-induced uplift along with Finn-Byrne pore pressure formulation is conducted to supplement the test results. The responses in terms of pore pressure and uplift of the underground structure using a sinusoidal input motion are compared with the model study results. The effect of diameter of the structure and the permeability of the soil on the liquefaction induced uplift is studied using parametric analysis. The numerical results reveal that the structure exhibits a larger upward displacement with the reduction in the permeability of the soil and an increase in the diameter of the structure.