路堤下CFG桩复合地基稳定性分析方法及试验验证

Analysis Method of CFG Pile Composite Ground Stability under Embankment and Test Validation

路堤下CFG桩复合地基稳定性分析方法尚不完善。基于桩体抗滑段受力平衡条件,开展考虑桩承水平净推力、桩承轴力和桩顶筋带约束作用的桩体抗滑效应分析。由CFG桩弯曲强度确定桩承极限水平净推力,通过引入桩体破坏不同步性的桩承水平净推力系数,提出能良好反映CFG桩弯曲破坏模式下复合地基稳定性分析的桩承综合力矩法,并结合土工离心模型试验进行验证。案例研究表明:路基工程CFG桩复合地基的抗滑力矩中,土体抗滑力矩占比54.8%~79.8%,桩体抗滑力矩占20.2%~35.5%,筋带抗滑力矩约9.7%;对于桩体抗滑力矩,由桩承轴力提供的抗滑力矩占比达86.9%~91.9%,由桩体弯曲强度和桩顶筋带约束作用引起的抗滑力矩占比约8.1%~13.1%;针对离心模型试验的极限和临界状态,采用桩承综合力矩法计算的地基稳定系数在0.98~1.06之间,适用性较好。

Given the imperfect stability analysis method of CFG pile composite ground under embankment,based on the force balance conditions of the anti-slip section of the pile,the anti-slip effect of the pile considering the net thrust of the pile bearing level,the axial force of the pile bearing and the constraint effect of the pile top rib belt was analyzed.The net thrust of the pile bearing limit level was determined by the bending strength of the CFG pile,while the net thrust coefficient of the pile bearing level was introduced by introducing the pile failure out of synchronization.A pile bearing comprehensive moment method was proposed,which can well reflect the stability analysis of composite ground under the bending failure of CFG piles,and was verified by combining geotechnical centrifugal model tests.The case analysis shows that in the anti-slip torque of CFG pile composite ground under embankment,the anti-slip moment of soil accounts for 54.8%~79.8%,with the anti-slip moment of pile accounting for 20.2%~35.5%,and the anti-slip moment of rib belt about 9.7%.For the anti-slip moment of the pile,the anti-slip moment provided by the pile bearing axial force accounts for 86.9%~91.9%,while the anti-slip moment caused by the bending strength of the pile and the binding effect of the pile top rib belt is about 8.1%~13.1%.According to the limit and critical state of the centrifugal model tests,the factor of ground stability calculated by the pile bearing comprehensive moment method is between 0.98~1.06,proving good applicability.