Numerical simulation of compaction effect during pile jacking in sand based on the coupled Eulerian-Lagrangian method
In order to explore the soil squeezing effect of the hydrostatic pile sinking process in sandy soil foundation,the Simsand critical state constitutive model of sand was introduced,and the coupled EulerianLagrangian(CEL)method was used to simulate and analyze the hydrostatic pile sinking process in sandy soil.The Sand parameters of the Simsand model werecalibrated based on published laboratory test data,which wereused in the simulation of centrifuge model tests of pile penetration in sand.The numerical model was verified by comparing the simulation results and the model test data.Overall,the influence range of pile jacking became larger with increases of the tip angle of a pile and the realative density of sand,the soil squeezing effect of the flat-bottom pile was more inclined to vertical forward in the process of pressing,thus mobilizing more soil resistance.Pile-foundation compression caused uplift in the near-surface soil layer,and the uplift of dense sand stratum was more significant than that of loose sand stratum.With the increase of depth,the vertical displacement of soil around the pile changed from uplift to downward movement and tendedto be stable,and the lateral displacement in dense sand was greater than that in loose sand.The diameter of the area affected by the soil squeezing effect decrease drapidly with the vertical downward direction of the pile end,decreased slightly with the vertical upward direction of the pile end,and increasedfirst and then decreased along the radial direction in dense sand.The influence range of pile jacking decreased repeadly and moderately along the downward and upward direction from the pile tip,repepectively,and increased first and then decreased along the radial direction.
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