Investigation of effectiveness of deep mixing method on seismic response of liquefiable soils using 3D numerical simulation

In recent decades, extensive studies have been conducted on mitigating the effects of liquefaction through various soil improvement methods. The Deep Mixing Method (DMM) is a widely used technique to improve mechanical properties of loose soils and reduce liquefaction effects. This research investigates the performance of DMM columns in reducing liquefaction effects through a parametric study using the finite element software OpenSees PL. In this study, the soil and DMM columns are modeled as a continuous three-dimensional medium considering nonlinear elastoplastic behavior. The influence of area replacement ratio, layout placement of DMM columns and shear modulus on excess pore water pressure, lateral displacement, horizontal acceleration, and stress-strain behavior in the liquefiable soil are investigated. Results show that an area replacement ratio of 20% or higher effectively reduces liquefaction effects. Furthermore, using DMM columns in a grid layout is more effective in reducing liquefaction effects compared to a single-column layout. However, employing DMM columns increases the acceleration transmitted to the superstructure at the ground surface.