Centrifuge Modeling for Seismic Behaviors of Pile Groups on Inclined Laterally Spreading Soils

Abstract eng:
The assessment of liquefaction hazard and the seismic design for the pile foundation in the inclined liquefiable soil layer is potentially very significant. Centrifuge tests of 50g are conducted to investigate the seismic behaviors of pile groups on the inclined liquefiable soils during earthquakes. The scenario input motions with peak shaking amplitudes of 0.24g and 0.99g (at prototype scale) were adopted in centrifuge tests. These centrifuge experiments simulate an inclined saturated layer of slope angle = arctg(1/2), and relative density of 89 % and 60%. The soil profile resting on stiff bedrock is made by de-aired dry sand saturated by de-aired motolose solution of 50 times the viscosity of water such that the deposit has the prototype permeability of sand. The model pile foundation consists of structure supported by a 2×2, 10 times diameter spacing pile group. A relative large crest residual lateral displacement of over 0.85m at prototype scale was measured after the test of strong shaking of 0.99g. It is found that the lateral displacement and bending moments of pile groups are much larger in laterally spreading soils than in non-liquefied soils. And the location for the max bending moment during shaking and residual bending moment transfer further down with the liquefaction and lateral spread of soils. The dynamic centrifuge tests proposed in this paper are applicable and reliable for simulating seismic performance of pile groups on the inclined liquefiable foundation.

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