桩基挤土过程对地铁隧道影响的多因素分析

Multi-factor analysis of influence of displacement pile on subway tunnel

基于有限元大变形和接触非线性分析,将挤土桩简化为离散刚体,研究桩基挤土施工过程导致邻近既有地铁隧道横截面的位移规律和桩体贯入过程中邻近既有隧道衬砌结构的位移变化规律。通过有限元计算结果与离心机模型试验结果的对比分析,验证采用的研究手段是合理的。同时研究桩−隧道间距、桩长、桩−土摩擦因数、隧道和土体弹性模量等因素改变时桩体贯入对衬砌结构的影响程度和范围。研究结果表明:桩−隧道间距、桩长、桩−土摩擦因数以及土体弹性模量对衬砌的位移影响较大,而隧道弹性模量对衬砌的位移影响较小。研究成果对地铁周边挤土桩及类似挤土工程施工时的地铁隧道保护问题具有指导意义。

Based on the nonlinear finite element analysis on large deformation and contact,the effect of displacement pile on adjacent existing subway tunnels was studied.The displacement pile was simplified as a discrete rigid body,and the influence of the adjacent existing tunnel lining structure during the penetration of the pile was studied.Through the comparison between the study results and the centrifuge model test,it was considered that the method was reasonable.Meanwhile,the influence extent and scope of the pile jacking on the lining structure under different condition were studied,as different pile-tunnel spacing,pile length,pile-soil friction coefficient,and tunnel and soil elastic modulus.The results show that pile-tunnel spacing,pile length,pile-soil friction coefficient and elastic modulus of soil have a larger impact on the displacement of the lining.The elastic modulus of the tunnel has little effect on the displacement of the lining.The achievement provided theoretical analysis means and guidance significance for tunnel protection encountering the construction of displacement piles and similar excavation engineering around the subway.