Numerical study on mitigation of liquefaction induced uplift of underground structure

Underground structures buried within liquefiable soil are often likely to get uplifted during an earthquake due to its relatively low unit weight and shallow burial depth. Therefore, there exists a need to come up with a mitigation technique to prevent the uplift of these underground structure, which could be easily applied in field. In this study, uplift mitigation of the underground structure by accelerating the pore pressure dissipation from the vicinity of the structure by replacement with more permeable sand is numerically studied using a finite difference program, FLAC3D. The response of a 5 m diameter structure which is buried at a depth of 1.1 times the diameter of the structure from the surface is studied. For this the whole soil model is subjected to 2010 Chile Earthquake. The cyclic behavior of the soil represented by FINN-model in which the pore pressure generated is measured from the volumetric strain induced by the ground motion. The effectiveness of the above mentioned methods are highlighted and are compared in term of pore pressure around the structure and the maximum uplift observed.