软弱砂层下的地铁隧道穿越建筑物的加固技术及注浆控制效果分析

地铁隧道在富水软弱砂层下穿越建筑物时,容易引起开挖面涌水突泥、围岩滑塌失稳以及建筑物不均匀沉陷等工程灾害。以青岛地铁枣李区间隧道软弱砂层带下穿建筑物工程为例,提出了全断面超前帷幕注浆、初支背后径向注浆及洞内补偿注浆联合加固技术。通过数值计算考虑注浆膨胀作用,分析了隧道下穿施工过程的地表变形及建筑物稳定性特性。研究表明:隧道在软弱砂层中采用全断面超前帷幕注浆会引起地表隆起现象,双线隧道地表呈现M型隆起变形,后开挖隧道变形值较大;地表建筑物在注浆膨胀作用下表现出正曲率变形,后开挖隧道正上方建筑基础最易发生破坏;穿越富水软弱砂层时不能一味提升注浆压力来提高地层刚度,应与现场监测结合进行施工控制。

Reinforcement Technology and Grouting Control for Metro Tunnel Crossing Buildings under Soft Sand Layer

When a metro tunnel crosses through buildings in rich water and soft sand layer,the engineering diseases are prone to occur,like mud outburst,water gushing in tunnel face,sliding instability of surrounding rocks and uneven settlement of buildings,etc.Based on the engineering practice of Qingdao metro Zaoli Tunnel that crosses buildings under soft sand layer,the construction control measures of full-face curtain grouting,radial grouting after primary supporting and compensation grouting are put forward.The stability of buildings and surface deformation characteristics have been researched by numerical simulation with consideration of the grouting expansion effect.The results show that surface uplift is caused by using full-face curtain grouting in soft sand layer,the double line tunnel presents "M"type surface uplift deformation,and the deformation of tunnel of later excavation is bigger.The surface buildings influenced by grouting expansion show positive curvature deformation,and building foundation is easily destroyed above the tunnel of later excavation.In the process of crossing through rich water and soft sand layer,the method of ascending grouting pressure to improve the ground stiffness could not be adopted blindly,and field monitoring should be insisted for construction control.