跨不同倾角软弱层隧道围岩变形规律

山区隧道与地下工程的建设中多会穿越软弱夹层或破碎带等软弱地层。此类软弱地层几何形态变化大,力学性能差,隧道开挖后的收敛变形往往难以控制,这也成为山岭隧道施工以及结构设计的难点所在。本文着眼于软弱地层倾角对隧道围岩开挖变形的影响规律,利用模型试验,对无支护条件下软弱层围岩的拱顶、拱腰进行研究,监测了软弱层倾角分别为45°、60°、90°、120°、135°时隧道开挖造成的收敛变形；并结合数值模拟方法,进一步对比验证了模型试验的检测规律。结果表明：软弱层倾角对隧道围岩变形的影响十分显著。随着软弱层倾角的增加,隧道拱顶、拱腰以及仰拱的围岩位移先减小后增大。不同软弱层倾角下,通过归一化处理发现,拱顶和拱腰位置数值计算和模型试验的围岩位移变化结果呈现出高度的一致性。且根据监测面的塑性区云图,剪切破坏的区域贯通,分布于隧道一周,其面积随着软弱层倾角的增加,先减少后增大。

Research on Deformation Law of Surrounding Rock in Tunnels Crossing Soft Layers with Different Inclinations

In the construction of mountain tunnels and underground projects, most of them will pass through weak layers such as weak interlayers or broken zones. The geometric shape of this kind of weak stratum changes greatly, the mechanical properties are poor, and the convergent deformation after tunnel excavation is often difficult to control. This has also become the difficulty of mountain tunnel construction and structural design. This paper focuses on the influence of the weak stratum dip on the tunnel"s surrounding rock excavation deformation, and uses model tests to study the vault and vault of the weak surrounding rock under unsupported conditions. The inclination angles of the weak stratum are 45° and 45°, respectively. Convergent deformation caused by tunnel excavation at 60°, 90°, 120°, and 135°; combined with numerical simulation methods, the detection rules of the model test are further verified by comparison. The results show that the inclination angle of the weak layer has a significant effect on the deformation of the tunnel surrounding rock. With the increase of the inclination of the weak layer, the surrounding rock displacements of the tunnel vault, vault waist and invert arch decrease first and then increase. Under different weak layer inclination angles, through normalization processing, it is found that the numerical calculation of the vault and vault waist position and the surrounding rock displacement change results of the model test show a high degree of consistency. And according to the cloud map of the plastic zone on the monitoring surface, the shear failure area is through and distributed around the tunnel, and its area first decreases and then increases with the increase of the inclination of the weak layer.