基于双剪强度理论土拱效应的基坑支护桩间距分析

在分析桩间土拱效应形成机理的基础上,以圆形支护桩为研究对象,利用合理拱轴线和起拱点土体破坏面等几何特征,建立抛物线土拱分析模型,通过桩间土拱静力平衡条件和双剪强度理论来确定桩间距,推导出圆形支护桩的合理桩间距计算公式,桩间净距随桩后土体粘聚力或内摩擦角的增大而增大,却随着桩后主动土压力或中主应力参数m的增大而减小,且随着参数m的增大,桩后主动土压力是逐渐增大的.最后通过工程实例计算支护桩间距,并与有限元法和规范法计算结果进行比较,验证了基于双剪强度理论土拱效应的基坑支护桩间距计算结果的合理性和安全性.

Analysis of the spacing between retaining piles based on twin shear strength theory soil arching effect in pit

Based on nalysis of the formation mechanism of the soil arching effect and according to the geometrical features of rational arch line and the failure surface of soil at the edge of arch foot,the calculation model of parabolic soil arching is put forward for a circular pile.The static equilibrium equation and twin shear strength theory are utilized to determine spacing between piles respectively.The rational calculation formula of spacing between piles is obtained.The calculation results show that the spacing between piles increases with the increasing cohesion or internal friction angle of soil behind piles and decreases with increasing active earth pressure behind piles or parameter m.Furthermore,the active earth pressure increases with the increasing parameter m.Through calculation of the practical project,the calculation results of twin shear strength theory soil arching effect are compared to those of the FEM and standard calculation method.The results show that the calculation results of twin shear strength theory soil arching effect are rational and safety.