小净距立体交叉隧道流固耦合研究

Study on Fluid-Solid Coupling of Overlapping Tunnels with Small Clear Spacing

以青岛地铁2号线下穿地铁1号线为背景，采用试验法与数值模拟方法相结合，对小净距立体交叉隧道进行流固耦合研究。结果表明：①施工扰动产生应力峰值后围压碎裂区挤密，导致渗透作用减弱，当岩石受到的应力峰值达到一定值时，岩石渗透系数趋于稳定，不随水压的变化而变化；②渗流造成的地表沉降增量大于开挖造成的地表沉降增量，且沉降槽宽度也明显增大；③开挖是隧道变形增大的主要因素，在渗流作用下，隧道结构自身能够保持较高的稳定性；④隧道开挖造成围岩孔隙水压力急剧减小，在隧道周边形成漏斗状孔隙水压力区；隧道超前注浆支护有利于降低隧道周边孔隙水压力，减小地下水对隧道的影响。

In order to study the fluid-solid coupling of tunnels with small clear spacing, the Qing- dao Metro Line 2 # and Metro 1 # northern extension line were selected as an example for testing and numerical simulation. Results show that the compaction area of confining pressure is compac- ted after reaching the peak stress resulted from construction disturbance, which leads to the weakening of permeability. When the peak value of rock stress reaches a certain value, the per- meability coefficient of rock tends to be stable and does not change with water pressure. The sur- face settlement caused by seepage is larger than that caused by excavation, and the width of the settlement trough is also increased apparently. Excavation is the main factor for tunnel deformation, and the tunnel structure can be highly stable under seepage. The pore water pressure of surrounding rock decreases sharply due to tunnel excavation, and a funnel-shaped pore water pressure zone is formed around the tunnel. The tunnel grouting support is beneficial to reduce the pore water pressure around the tunnel and reduce the influence of groundwater on the tunnel.