钢护筒与泥浆护壁桩孔稳定性离心模型试验及数值模拟OA

The deformation and instability process of pile boreholes in saturated sand layers was investigated through centrifuge model test and finite element simulation,aiming to study pile borehole stability under combined steel casing and slurry support in soft strata.Based on centrifuge model test results,high-resolution deformation images were analyzed using particle image velocimetry(PIV)to obtain the displacement field of the surrounding soil,thereby identifying the failure mode of the pile boreholes.Numerical simulations using the finite element strength reduction method were further conducted to explore the influence of borehole geometry,soil parameters,and slurry properties on the safety factor and failure modes.The results indicate that under the combined support of steel casing and slurry,the failure mode of pile boreholes exhibits a composite pattern,characterized by an inverted frustum-shaped failure originating from the slurry surface and a cylindrical failure surface extending to the ground surface.The embedment depth of the steel casing has a negligible impact on the inclination angle of the frustum,which is primarily governed by slurry support pressure and soil strength.During pile borehole excavation with steel casing and slurry support,two failure modes may occur,namely upper-layer sliding and basal heave.The support pressure generated by the slurry effectively suppresses basal failure,while the steel casing restrains lateral soil deformation displacement.