An investigation of the dilation effect of soil on liquefaction-induced settlement

In this research, dilation effect related to density and confining stresses during liquefaction on structural settlement is investigated using OpenSees. Therefore, a sand layer with different dilation angles and surface load is considered. The numerical model presented in this research, calculated the excess pore water pressure based on fully coupled effective stress analysis during seismic loading. Model parameters were selected and verified using the results of VELACS centrifuge tests. The results show that by increasing the dilation angle, the pore water pressure decreases and the liquefaction-induced settlements decrease. The decreasing trend of settlement with increasing dilation angle tends to a constant value, so that at high densities with increasing dilation angle, little changes in settlement is observed. Also, the dilation angle is calculated based on the preshear mean effective stresses and compared with the dilation angle caused by the stresses during liquefaction. The comparison shows that for relative densities less than 60%, the dilation angle obtained from preshear effective stress is more than the confinig stress based method during liquefaction.