突变地质界面围岩稳定性分析及盾构推力判定研究

STABILITY OF SURROUNDING ROCK AND THRUST CALCULATION OF SHIELD PASSING THROUGH GEOLOGICAL MEDIUMS

以济南轨道交通R1线隧道下穿腊山河段为工程背景,采用理论计算与数值分析相结合的方法,分析盾构穿越不同介质的围岩稳定性特征、盾构推力影响效应及界面参数敏感性。研究结果表明:盾构穿越介质交界时,围岩拱顶沉降表现为先增大后减小,管片主应力呈现先增大后减小又回弹的规律,界面效应影响范围主要为界面前4 m至后10 m;当安全系数为2时,维持岩石介质、土体介质、河道段开挖面稳定的支护应力比分别为0.24~2.80,0.34~1.65,0.54~1.40;岩–土界面效应随介质刚度比和界面倾角的增大而增强,当k≥4和θ≥20°时,界面围岩的推力扰动敏感性更加显著。研究成果对深入研究突变地质界面下开挖面稳定性和灾害预防控制具有重要指导意义。

In the tunneling of the Jinan rail transit line R1 passing under Lashan River,the stability of surrounding rock,the effect of shield thrust and the sensitivity of interface parameters were analyzed employing both the theoretical calculation and numerical method. The study showed that,as the shield passed through the medium interface,the settlement of surrounding rock at arch crown increased firstly and then decreased,while the principal stress in the lining segment increased firstly,then declined and rebounded. The interface effect reached 4 meters to the front and 10 meters in behind. If the safety factor was 2,the support stress ratios maintaining the stability of rock medium,soil medium and excavation face of watercourse were 0.24–2.80,0.34–1.65,0.54–1.40,respectively. The rock-soil interfacial effect was found to increase with the increase of stiffness ratio of medium and interface dipping angle. Especially in the situation of k≥4 and θ ≥20°,the disturbance sensitivity of interface surrounding rock thrust became more significant.