黏性土桩间土拱效应计算与桩间距分析

土拱效应是安全经济地发挥抗滑桩等非连续支挡结构的支护功能的重要前提，桩间距与成拱作用密切相关。利用合理拱轴线几何特征与受压破裂角方位，通过力学概念分析，将黏性土土拱计算的平衡条件和强度条件综合简化为以拱脚处拱圈轴向压应力表达的形式。继而从最少且最易获得的土工材料参数（内聚力c、内摩擦角?）出发，根据轴向压应力与矢跨比函数关系，利用摩尔-库仑强度准则，推导了拱曲线与桩间距上下限的简便计算式，再以此进一步探讨了考虑土拱效应三维稳定的桩间距校核，并以工程实例验证，以对土拱效应的估算提供简便清晰的计算方法。

Analysis of soil arching effect between adjacent piles and their spacing in cohesive soils

Soil arching effect is an important precondition of adjacent pertaining or anti-sliding piles working safely and cost-efficiently. In cohesive soils, the spacing between adjacent piles is related to arching effect. By means of the analysis of mechanical concepts, taking geometrical characteristic of arch line and the fracturing face direction angle of Mohr-Coulomb failure to account, the force-balancing condition and strength condition are integrated and simplified to a uniform expression, which is only presented by the normal stress on the cross section plane of arch foot. Based on Mohr-Coulomb failure criterion, the least handy soil strength parameters which only including cohesion c and internal friction angle ?, according to the relationship between the normal stress and arrow-span ratio, the arch line and spacing between piles are obtained. Furthermore, the depth stable condition of soil arch is discussed, pile spacing can be emended more rationally. The application consists with practice projects to a certain extent. A concise estimate method to soil arch effect may be put forward.