3D Seismic Numerical Modeling of Infrastructure on Liquefiable Soils

3D seismic numerical modeling using the FLAC3D program was carried out for three representative cases: 1) an embankment dam on a liquefiable layer, 2) a berth structure consisting of quay wall supported by anchor walls and tie-rods subject to soil liquefaction, and 3) a long pier consisting of vertical and battered steel pipe piles supporting deck structures. Soil-cement grids were considered in case 2 to mitigate liquefaction effects. The P2PSAND soil constitutive model, specifically designed for 3D modeling of liquefied soils, was employed to represent liquefiable soils. The P2PSAND model is based on the framework of the DM04 model and is a criticalstate compatible and plasticity model utilizing bounding surface theory. The model can simulate non-linear response, liquefaction triggering and strength reduction of the soils during earthquake. Soil-cement grids of various sizes were modeled in 3D to evaluate the method’s efficiency to reduce liquefaction and provide insight into the performance of the system. The structures were simulated with their 3D geometries to best evaluate the 3D soil and structure interaction. The effects of the earthquake direction, seismic wave ropagation to surface, and sizes of soil-cement grids were also presented and discussed.