高水压盾构隧道漏砂漏泥细观机理及诱发地层暗穴评价方法

Cross-sea shield tunnel can easily leak at the joint under high water pressure. This leak will bring about sand-mud leakage and great deformation of surrounding strata additionally, which lead to catastrophe. The micro-force between dynamic seeping water and sand-mud particles has not been considered in the current research of seepage mechanism at shield tunnel joint. Studies on the influence of tunnel leakage on the surrounding strata are mostly based on the seepage problems without considering the fluid-solid dynamic coupling effect. In this project, the mesoscopic mechanism of sand-mud leakage at the tunnel joint under high water pressure is studied by solving the motion control equation between fluid and sand-mud particles based on sediment dynamics theory. The discriminate indexes and criterion on leakage are proposed combined with experiment methods. The inducement mechanism of the hidden-hole in surrounding strata caused by sand-mud leakage is revealed. Considering the relation between sand-mud leakage quantity and time in different joint positions, an expression is established among head pressure, gap width and particle size at the worst leakage location in entire leaking process. The influence partition of sand-mud leakage at the hidden-hole of surrounding strata is proposed, and the assessment method of the stabilized soil arch is also raised. Based on the parametric study of the leakage judgement indexes at different positions, a fine control method is proposed, and a parametric optimization process of repairing the hidden-hole with grouting is also developed.

在高水压作用下的跨海盾构隧道接头处一旦漏水极易诱发漏砂漏泥，导致周围地层出现大变形而产生灾变。目前关于盾构隧道接缝渗漏机理的研究并未考虑动水渗漏与泥砂颗粒的细观作用力，有关渗漏对周围地层的影响研究也未考虑动水与泥砂颗粒的两相耦合效应。本项目通过求解基于泥砂动力学理论改进的流体与泥砂颗粒运动控制方程，研究高水压下盾构隧道接缝漏砂漏泥的细观机理，结合试验提出高水压下接缝漏砂漏泥的判定指标与判定准则；揭示漏砂漏泥对周围地层暗穴的诱发机制并绘制不同位置接缝漏砂漏泥量与时间关系曲线，建立最不利位置处开始漏砂漏泥直至形成稳定土拱的水头压力、漏点宽度、颗粒粒径间的全过程关系表达式；提出漏砂漏泥对周围地层暗穴的影响分区以及稳定土拱的评价方法，建立基于不同位置的漏砂漏泥判定指标敏感性的精细化控制方法，提出注浆修复暗穴的参数优化流程。

在高水压作用下的跨海盾构隧道接头处一旦漏水极易诱发漏砂漏泥，导致周围地层出现大变形而产生灾变。本项目研究高水压下盾构隧道接缝漏砂漏泥的细观机理，结合模型试验揭示不同位置接缝漏砂漏泥量与时间的关系；提出漏砂漏泥对周围地层暗穴的影响分区以及稳定土拱的评价方法，建立基于不同位置的漏砂漏泥判定指标敏感性的精细化控制方法。研究结果表明，拱脚缝渗漏最难形成稳定土拱。稳定应力土拱形成后，隧道内不再漏砂且平均有效主应力基本恢复至漏砂前。依据砂颗粒运动特征将隧道围岩分为侵蚀区、位移区和稳定区，侵蚀区水平向影响长度与压力水头和漏缝埋深正相关；漏缝位于拱脚、压力水头增加1倍隧道直径时，侵蚀区水平向长度增长率为45%；压力水头达到3.1倍隧道直径、渗漏位置由拱顶移至拱脚时，侵蚀区水平向长度增长率为32%。