嵌岩桩桩端极限承载力研究

Research on the Ultimate Bearing Capacity of Rock-Socketed Pile End

应用广义非线性统一强度理论和滑移线场方法,基于Meyerhof求解深基础极限承载力方法得出的地基破坏滑移面模式,推导出嵌岩桩桩端极限承载力公式,并对承载力随滑移面倾角及嵌岩比的变化规律进行研究,分析嵌岩比、中主应力系数、过载系数等因素对桩端极限承载力的影响。结果表明:桩端极限承载力系数随着嵌岩比的增加而呈非线性递减趋势,且递减幅度越明显。随着中主应力系数的增大,极限承载力也随之提高。承载力系数在嵌岩比n较小时,随着过载系数hm的增大而增大;当嵌岩比n较大时,则随hm的增大而减小。现行规范所定义的桩端承载系数偏于安全。

Based on the slip surface model of foundation damage used in the Meyerhof solution for the ultimate bearing capacity of deep foundation, the ultimate bearing capacity at the tip of a pile that is embedded in rock is deduced by applying the generalized nonlinear unified strength criterion and slip line principle for resolving the differential equation systems which govern the stress field. Then, the variation laws of end bearing capacity with sliding surface angle and embedment ratio are studied. The impacts of intermediate principal stress and overload factor are discussed in the analytical solution. Results show that the end bearing capacity decreases nonlinearly with the embedment ratio, but increases with respect to the intermediate stress parameter. And the bearing capacity factor increases with the overload coefficient h m when the embedment ratio n is smaller, but decreases while the embedment ratio is greater. The end bearing capacity defined by current pile design code is conservative according to the calculation results.