Three Dimensional Numerical Modelling of Stone Column to Mitigate Liquefaction Potential of Sands

Liquefaction is one of the most essential causes of failure of transportation infrastructures, especially the road and railroad based on saturated fine sand substrates under seismic conditions. Meanwhile, applying stone columns in a group form is considered as a method to control this phenomenon. To do so, Model No (1) of VELACS project, including NEVADA sand with relative density of %40, was first evaluated numerically using FLAC3D, in which finite difference and sufficiency of Finn constitutive model in liquefaction simulation was shown. Then, sensitivity analysis was performed to examine its radius and depth of influence on reducing excess pore water pressure by imposing a stone column in the center of the model and changing its diameter. In the final step, sensitivity analysis was performed on their efficiency to control liquefaction by simulating the group stone column with square layout and changing diameter of columns and their center-to-center distance. The results of numerical analyses show that the performance of the single stone column increases in reducing excess pore water pressure by increasing depth. Generally, it can be stated that at the depth of 1.25 m and 2.5 m the effective area of the column is 3 and 4 times bigger than the stone column diameter. Columns distance proportion to stone columns diameter (s/d= 2, 3, 4, 5) was evaluated for the group stage. Moreover, the single manner in the group forms more effective than a single column. The group performance of columns appeared to be better than the singular ones.