Effect of grid-form deep soil mixing on the liquefaction-induced foundation settlement, using numerical approach

Liquefaction occurs in loose saturated sand layers, inducing quite considerable damage to the existing buildings and civil infrastructures. In the last few decades, scientific committees in geotechnical engineering have focused on methods for liquefaction remediation, using different ground improvement techniques based on various improvement principles. Deep soil mixing (DSM) with a grid pattern was developed in the 1990s for liquefaction mitigation, in which a grid of stabilized column walls performs the function of restricting the generation of excess pore water pressure (EPWP) by confining the movement of the soil particles during an earthquake. The effect of DSM improvement with a grid pattern on foundation settlement and EPWP generation was investigated parametrically herein, using a numerical model developed in GiD + OpenSees interface V2.6.0. The validity of the model was evaluated by comparing the results obtained from the numerical model with the results from an experimental centrifuge study. The three-dimensional finite element model estimated a 75% reduction in settlement of the foundation rested on the improved ground as compared to the unimproved case. The results also indicated that the grid wall spacing, the diameter of columns, soil relative density, and the shear modulus ratio between DSM columns and the enclosed soil play a vital role in the liquefaction occurrence and volumetric strains.