荤素搭配咬合桩支护结构受力变形机制的研究

Mechanism of stress and deformation of the supporting structure of secant piles composed of the reinforced concrete piles and plain concrete piles

本文以杭州至富阳城际铁路标段隧道工程为研究背景,对荤素搭配咬合桩支护结构在基坑开挖过程中受力变形机制展开研究。利用有限元分析软件ABAQUS建立咬合桩支护结构数值模型,根据计算结果对支护结构的变形、内力等承载特性进行分析;进一步对比了荤桩和素桩在不同开挖阶段的应力状态,对素桩在咬合桩工作过程中对承载性能和抗弯刚度的贡献、素桩和荤桩的协同工作机制等问题进行探讨。研究结果表明,当咬合桩截面弯矩过大,素桩受拉区边缘混凝土会开裂并退出工作,但其受压区混凝土仍能承担一部分弯矩,咬合桩的实际承载力表现介于钢筋混凝土排桩与等效刚度地下连续墙之间。

Based on a tunnel project of Hangzhou-Fuyang intercity railway,this paper studies the stress and deformation mechanism of the supporting structure of secant piles composed of the reinforced concrete piles and plain concrete piles during the excavation of the foundation pit.Finite element analysis software ABAQUS is used to establish the numerical model of the secant piles supporting structure.According to the calculation results,the bearing characteristics such as deformation and internal force of the supporting structure are analyzed.Furthermore,the stress state of reinforced concrete piles and plain concrete piles in different excavation stages is compared.The contribution of plain concrete piles to bearing capacity and flexural rigidity and also the cooperative working mechanism of reinforced concrete piles and plain concrete piles are discussed.The results show that when the section bending moment of the secant piles is too large,the concrete at the edge of the tensile zone of the plain concrete piles will crack and withdraw from the work,but the concrete in the compression zone can still bear part of the bending moment,and the actual bearing capacity of secant piles is between that of reinforced concrete row piles and equivalent stiffness underground diaphragm wall.