深厚软土中抗滑桩的修正悬臂桩计算方法

Modified cantilever pile method for anti-sliding pile in deep soft soil

大面积堆填或开挖时深厚软土地层内部常产生较大滑移,这为该类地层中考虑桩土作用的抗滑桩分析带来较大困难。考虑深厚软土的滑移性状,针对既有悬臂桩法计算存在的问题进行修正,滑动面上部桩身受荷段的桩身荷载采用等腰三角形分布且极值点为极限侧土压力,设滑动面下部桩身锚固段上侧桩周软土为理想弹塑性以考虑软土大位移条件,下侧为弹性状态,并通过位移叠加原理对传统方法求解产生滑动面不连续的缺陷进行修正。通过现场桩侧堆载试验验证,修正悬臂桩法的弯矩和位移计算结果较好,桩顶位移误差小于3%,桩身最大弯矩误差小于10%。所提方法有助于深厚软土地层抗滑桩的设计和计算。

Large slip often occurs in deep soft soil during large area filling or excavation,which brings great difficulty to the analysis of anti-sliding pile considering pile-soil interaction.For this purpose,a modified cantilever pile method was proposed to overcome the problem in the calculation of the existing cantilever pile method considering the sliding behavior of deep soft soil layer.The soil pressure of the pile passive loading segment adopts an isosceles triangle distribution,and the maximum value is identical to the ultimate lateral soil pressure.The soft soil around the pile anchorage segment is assumed as ideal elastic-plastic to consider the large displacement of the soft soil.In addition,the displacement superposition principle is applied to deal with the discontinuous displacements around the sliding surface existed in previous methods.The displacement and bending moment results obtained by the proposed method are verified by in-situ pile side loading test.The displacement error of pile top is less than 3%,the maximum bending moment error of pile is less than 10%.The proposed method is helpful for the design and calculation of anti-sliding piles in deep soft soil layer.