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在软弱围岩中进行隧道开挖,往往因岩体应力过高或变形过分而导致围岩失稳破坏,并进而引发隧道塌方事故。本文以Ⅳ类软弱破碎围岩为参照对象,首先将其等效为单一均值地层,再利用相似材料对其进行模拟,随后利用活动门试验模拟隧道的开挖,研究了隧道开挖过程中围岩的破坏模式及其渐进破坏特征。试验结果表明,软弱围岩中隧道施工不可避免地会在隧道周边形成扰动区,而真正塌落成拱的只是该扰动区的一部分;在隧道开挖过程中,岩体内部的裂纹扩展与破坏,就会对应地表岩体的急剧下降;隧道开挖后,拱顶上方的岩体中存在一压力拱,位于该拱下方的岩体处于松弛状态,而拱上方的岩体则处于挤压状态,并且该压力拱随着外界荷载的增加呈外延趋势。
Tunnel excavation in weak surrounding rock often leads to instability of surrounding rock due to over-stress or over-deformation of rock mass, which in turn triggers tunnel collapse. In this paper, we take the Ⅳ type of weak crushing surrounding rock as the reference object, first of all, it is equivalent to a single mean stratum, and then use similar materials to simulate it, and then use the activity gate test to simulate the tunnel excavation, the tunnel excavation process Rock failure modes and their progressive destruction characteristics. The results show that the tunnel construction in the soft rock will inevitably form a disturbance zone around the tunnel, but the real arch is only part of the disturbance zone. During the tunnel excavation, the crack propagation and destruction in the rock mass, There will be a sharp decline in the rock mass corresponding to the surface. After tunneling, there is a pressure arch in the rock mass above the vault. The rock mass located below the arch is in a relaxed state, while the rock mass above the arch is in a squeezed state, And the pressure arch shows an outward trend with the increase of external load.