不同埋深条件下盾构施工扰动试验研究

Experimental study on stratum disturbance of shield construction under different tunnel depth conditions

随着城市地下空间开发规模不断扩大,盾构施工诱发的地层扰动对地下既有建(构)筑物及周边环境的安全产生了重要的影响。通过自主研发盾构掘进试验装置,实现了不同地层应力水平的加载,分析了不同埋深条件下盾构施工地层扰动的变化规律及影响范围。研究结果表明:隧道周围地层中土压力变化率随着距隧道水平距离的增大而逐渐递减;盾构掘进完毕后土压力相对于初始土压力减少了约20%~40%;埋深比变化对拱顶、拱底处的土体应力路径影响较小;定义了基于土压力力变化的地层扰动度,随埋深比的增大,地层扰动度逐渐减小,说明深埋条件会降低盾构开挖对地层的扰动作用;盾构掘进完毕后,扰动作用的竖向影响范围高度介于隧道上下0.5D~0.8D(D为隧道直径)之间,当盾构到达监测断面时水平扰动范围宽度约为0.5D,盾构穿越远离后近似为1.2D~1.5D。

With the continuous expansion of urban underground space development,stratum disturbance induced by shield construction has an important impact on the safety of existing underground structures and surrounding environment.Through the independent research and development of the shield tunneling test device,the load of different stratum stress levels was realized,and the change law and influence range of the stratum disturbance in shield construction under different burial depth conditions were analyzed.The results show that the change rate of earth pressure in the strata around the tunnel decreases with the increase of the horizontal distance from the tunnel.The ratio of soil pressure after shield tunneling to initial soil pressure is about 60%-80%.The change of buried depth ratio has little influence on the soil stress path at the vault and bottom.The stratum disturbance degree based on the change of stress is defined,and the stratum disturbance degree gradually decreases with the increase of the burial depth ratio,indicating that the deep burial condition will reduce the disturbance effect of shield excavation on the stratum.After the completion of the shield tunneling,the height of the vertical influence range of the disturbance is between 0.5D and 0.8D above and below the tunnel(D is the diameter of tunnel),the width of the horizontal disturbance range is about 0.5D when the shield reaches the monitoring section,and approximately 1.2D to 1.5D when the shield passes far away.