Numerical Study on the Performance of Shallow Foundation on Liquefiable Soil During an Earthquake
摘要
The process of shearing loose, saturated sand raises the pore water pressure. When the extra pore water pressure reaches the effective overburden stress, the soil liquefies or behaves like a fluid, deforming without gaining shear strength. The dynamic response of sand was simulated in this study utilizing finite element method (FEM) analysis and a critical state compatible constitutive model calibrated for Ottawa sand. The liquefaction susceptibility and settling behavior of structures built on such soil were examined using OpenSees. The impact of ground characteristics (thickness of top and bottom non-liquefiable layers) and structural parameters (foundation width, structure height, and bearing pressure) on the liquefaction induced settlement of shallow foundations was examined numerically and parametrically. The findings showed that the acceleration time history of ground motion controls the rate of settlement, with peak acceleration times resulting in the greatest amount of settlement. It was discovered that shear induced displacement was crucial to structural settlement, indicating that empirical techniques created for free field settings might not be accurate. The results also showed that, in contrast to popular belief, liquefaction induced settlement is not always lessened by wider foundations. Higher contact pressure was also shown to promote settlement, possibly as a result of ratcheting effects brought on by shear. The thickness of the non-liquefiable crust was found to have a greater effect on settlement than the thickness of the non-liquefiable base among the ground parameters examined.