堆载下单桩负摩阻力工作性状非线性数值分析

NONLINEAR NUMERICAL ANALYSIS ON NEGATIVE SKIN FRICTION BEHAVIOR OF SINGLE PILE UNDER SURFACE LOADS

利用三维非线性数值方法对一算例在堆载作用下桩侧负摩阻力进行了计算分析。计算结果揭示了摩擦型、端承型桩负摩阻力工作性状的异同;分析了堆载速度、桩顶荷载对负摩阻力的影响:堆载越快,负摩阻力越小;在无桩顶荷载作用下,由负摩阻力引起的下拉荷载最大,可视为常规方法设计的上限值;桩顶荷载与堆载施工顺序对负摩阻力的影响也很大,先施加桩顶荷载,后进行堆载所产生的负摩阻力最大,反之最小。

Three dimensional nonlinear analyses on negative skin friction of a single pile was carried out for a specific case under surface loads.The results show the similarities and differences of negative skin friction behavior between friction pile and end-bearing pile.It was found that loading velocity of surface loads and the pile working loads influence negative skin friction very much： the more the loading velocity,the less the negative skin friction;the dragload of a pile without pile axial load is the ultimate value and could be considered as an upper limit for conventional analysis.Moreover,combinations of pile working load with surface load lead to change the pile axial force,namely,application of the working load and then application of the surface load can cause a maximal negative skin friction.And on the contrary case,the minimum.