上海地区桩基侧摩阻力折减原因分析

Analysis on the Reduction Causes of Pile Shaft Resistance in the Shanghai Area

针对上海地区以第⑤层黏土为持力层的桩基,其桩侧摩阻力易发生折减的现象,本文利用现场单桩静载荷对比试验,通过对荷载—沉降、轴力—深度、桩侧阻力—深度、桩侧阻力—桩土相对位移等关系地分析,找出其中的规律特征;同时结合桩侧阻力发挥规律、桩侧软化效应和桩端强化效应的理论研究,最后得出结论,折减的原因实际上是桩侧摩阻力应变软化效应和桩上下部极限侧阻力的发挥不同步造成.

In the Shanghai area, it tends to emerge reduction of pile shaft resistance when the tip of the pile is in the fifth soil. Based on the field static load test data of single pile, this paper analyzed the relationship between load and sedimentation, axial force and depth, side resistance and depth, side resistance and the rela- tive displacement of the soil core and piles. Combined with the existing theoretical study about the law of side re- sistance, the shaft resistance softening and the enhancing response around the pile end, the paper concluded that the reduction is actually caused by shaft resistance strain softening and the asynehronism of the ultimate side re-sistance in different position of the piles.