Numerical Modeling of the Effects of a Group of Micropiles in Liquefiable Soils

As micropiles, small-diameter (d < 300 mm) piles installed in problematic liquefiable soils, are widely used in seismic areas, studying their behavior during an earthquake is of great importance. To validate the numerical modeling accurately, this study used the finite difference method to investigate the liquefaction phenomenon with the help of the FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions) Software and compared the results with those of Test No. 1 of the VELACS international project. Next, to check the efficiency of micropiles in liquefiable soils, such influential parameters as their number, presence/absence of superstructures on them, their spacing-to-diameter ratio (s/d) were investigated and the results indicated that increasing their number highly reduced the excess pore water pressure. Although the s/d effects were ignorable, smaller spacing (denser) micropiles reduced the settlement more in the presence of live loads.