超浅埋大断面隧道施工力学行为研究

Study on Construction Mechanical Behavior of Super Shallow Large Section

为防止隧道在富水、软弱围岩等特殊地质环境下穿既有建(构)筑物时诱发坍塌、冒顶、支护侵入隧道限界、地表沉降过大、发生受力破坏等工程灾害,以厦门祥岭隧道下穿成功大道和福厦铁路为工程背景,利用有限差分法研究祥岭隧道双侧壁导坑法施工条件下的具体力学行为。研究结果表明:(1)两条收敛曲线发展规律大致相同,曲线4的收敛重心偏下,其产生的原因可能与模型假设有关,假设模型两端固定,没有发生位移,而数值分析过程中锚杆垂直作用于边墙,而非施工所要求的锁脚锚杆,所以上导坑开挖后,拱脚有一定位移;(2)与左壁不同,右壁虽然也是圆弧形,不过曲率半径较大,在理论推导模型中作为直杆考虑,误差较小,所以最终收敛变形曲线较为接近。

In order to prevent from the engineering disaster such as collapse,roof fall,invasive supporting surface clearance,settlement of tunnel when crossing the existing tunnel built in special geological environment in rich water and soft rock under the building( structure),the finite difference method is used to analyze the mechanical behavior of rock mass and lining structure against Xiangling tunnel crossing Chenggong Avenue and Fuzhou-Xiamen high railway.The results show that:(1) the development rules of two convergence curves are roughly the same,the convergence curve4 lower center of gravity,the reason may be related to the assumption of the model,the hypothetical model with two fixed ends,no displacement,and in the process of numerical analysis,the bolt acts perpendicular to the side wall,instead of feet lock bolt construction requirements so,on the tunnel after excavation,the arch of the foot has a certain displacement;(2) the left wall and right wall is different,although the circular arc shape,but a larger radius of curvature,in the theoretical model as a straight rod,the error is small,so the final convergence deformation curve is close.