盾构掘进引起砂土沉降及管道脱空模型试验研究

Experimental Modeling of Sand Settlement and Pipeline Void Formation Caused by Shield Tunneling

为系统研究盾构隧道开挖引起的土与管线相互作用问题,揭示盾构掘进过程中地层位移的复杂性及管土界面接触状态变化规律,采用缩尺物理模型试验方法,制作可监测管线沉降、管底脱空和管底土压的模型管线,通过拔管的方式来模拟盾构隧道掘进过程,依次开展盾构掘进引起砂土深层沉降试验、管线响应与管土脱空试验。试验结果表明:1)盾构隧道开挖引起的深层土体沉降仍符合高斯分布,沉降槽宽度参数与地层损失率均随地层埋深呈现非线性变化。2)试验证实了在较大的地层损失条件下容易出现管土脱空现象,隧道开挖引起的最大管线变形和管底脱空值均随管线埋深增大而增大,而管底脱空范围递减。3)当管线挠曲较小时,管线与土体保持紧密接触;随着盾构掘进,在开挖面距管线1.5倍隧道直径处其底部开始出现脱空现象,开挖面距离管线1倍隧道直径至离开管线1倍隧道直径是脱空的主要发展阶段。

To systematically investigate the interaction between soil and pipeline caused by shield tunneling and to elucidate the complexities of ground displacement and the changing state of pipe-soil interface contact,a scaled physical model test is employed.This model pipeline is designed to monitor pipeline settlement,pipe void formation,and subsoil pressure.Furthermore,shield tunneling process is simulated through tube extraction,followed by sequential tests on deep soil settling,pipeline response,and pipe soil voiding.The experimental results reveal the following:(1)Deep soil settlement caused by shield tunneling conforms to a Gaussian distribution,with the width of the settlement and volume loss exhibiting nonlinear changes with soil depth.(2)The tests confirm that significant volume loss leads to the formation of voids.The maximum deflection of the pipeline and the void height increase with burial depth,while the void width decreases.(3)During tunneling,voids begin to form at the pipeline bottom when the excavation face is approximately 1.5 times the tunnel diameter away.The primary development of voids occurs within one tunnel diameter from the pipeline.