硬岩地区浅埋暗挖隧道施工地表沉降特征模型试验研究

Model Test Study on Ground Settlement Characteristics Caused by Shallow Buried Tunnel Construction in Hard Rock Area

城市地铁隧道开挖会对围岩产生扰动并破坏其稳定性,严重时甚至引起地层失稳而造成路面塌陷事故。为研究城市地铁浅埋暗挖隧道施工所引起的地表沉降基本特征,以青岛硬岩(花岗岩)地层为例,通过室内三维模型试验对隧道开挖过程进行了动态模拟,总结出不同工况下开挖所引起的地表沉降规律,同时将数值模拟结果与室内试验结果作对比分析。研究结果表明:浅埋隧道的开挖会引起以地表沉降为主的地层变形,其横向沉降数值分布会呈现出“两侧小中间大”的沉降槽,这与数值模拟结果较为相符,即隧道正上方的沉降变形最大,越是偏离隧道中轴线则地表受开挖扰动越小;而纵向地表沉降则分为“缓慢变形”“剧烈变形”以及“变形稳定”三个阶段,上述阶段的影响范围基本维持在距掌子面-1.6D^1.6D(D为隧道洞径)。因此,试验所得结果可以应用在硬岩地区浅埋暗挖施工当中。

Excavation of urban subway tunnels will disturb the surrounding rock and destroy its stability.In severe cases,the formation will be unstable and result in road collapse accidents.In order to study the basic characteristics of ground settlement caused by the construction of shallow excavation tunnels in urban subways,took the Qingdao hard rock(granite)stratum as an example,the dynamic simulation of tunnel excavation process was realized by means of indoor 3D model test.The law of ground subsidence caused by excavation under different working conditions was summarized,and the numerical simulation results were compared with the indoor test results.The results show that excavation of shallow tunnels will cause deformation of the stratum dominated by ground settlement.The numerical distribution of lateral settlement shows a settlement tank with shape of small on both sides and large in the middle,which is more consistent with the numerical simulation results.That is,the ground settlement deformation directly above the tunnel is the largest.The farther away from the central axis of the tunnel,the smaller deviation of the ground affected by the excavation is.The vertical ground settlement is divided into three stages of slow deformation,violent deformation and stable deformation,with their influence range between-1.6D and 1.6D(D is the tunnel hole diameter)from the tunnel face.Therefore,the results obtained from the test can be applied to shallow excavation tunnels in hard rock areas.