深埋公路隧道复杂断面十字交叉施工稳定性数值分析

Numerical Analysis of the Stability of Deep-buried Highway Tunnels with Complex Cross Sections

以在建郑西高速伏牛山特长公路隧道为研究对象,采用MIDAS/GTSNX有限元分析软件模拟深埋隧道主洞、排风斜井及辅助横通道采用十字交叉的开挖方式,对交叉口围岩位移、初支结构与围岩间的相互作用以及支护结构受力的影响情况。结果表明:主洞开挖对十字交叉口沉降影响距离为(1.8~2.2)D1(D1为主隧道洞跨),横通道的开挖对交叉口沉降影响距离为(1.5~2.0)D2洞径(D2为辅助通道洞跨);随着横通道的开挖,交叉口各部位同时产生沿X轴正向的水平位移;辅助横通道的开挖使σ3最小值增长90.7%,最大剪应力τ值增长130.8%,应力集中区由斜井交叉口转至辅助横通道交叉口两侧拱腰;交叉段初期支护应力存在偏压现象,交叉段斜井顶部应力最大。

By taking the Funiushan super-long highway tunnel under construction on Zhengxi Expressway as an example,MIDAS/GTS NX finite element analysis software was adopted to simulate the deep-buried main tunnel.The exhaust inclined shaft and auxiliary transverse passage were simulated using a cross-cutting excavation method,and the displacement of the surrounding rock at the intersection,the interaction between the initial support structure and the surrounding rock,and the force of the supporting structure were analyzed as well.The results are as follows.The influence distance of the main tunnel excavation on the settlement of the intersection is(1.8~2.2)D1(D1 is the main tunnel span),and the influence distance of the excavation of the cross passage on the settlement of the intersection is(1.5~2.0)D2 tunnel diameter(D2 is Auxiliary passage tunnel span);with the excavation of the cross passage,each part of the intersection simultaneously produces horizontal displacement along the positive X axis;the excavation of the auxiliary cross passage increases the minimum value ofσ3 by 90.7%and the maximum shear stress The value ofτincreased by 130.8%,and the stress concentration area was transferred from the intersection of the inclined well to the arch on both sides of the intersection of the auxiliary cross passage;the initial support stress of the intersection was biased,and the top stress of the inclined well was the largest.