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在富水软岩地层中修建隧道容易出现突泥塌方,对施工及周边环境产生严重影响。北岗隧道围岩强度低且地下水丰富,在施工中多次遇到突泥涌水现象,出现了围岩大面积坍塌、地表开裂、地下水位下降等严重灾害问题。以北岗隧道为原型,开展了室内模型试验,再现了该隧道的破坏现象,研究了隧道突泥塌方的影响因素、破坏规律及影响范围。结果表明:(1)地表未出现裂缝时,隧道开挖导致的地表和地层内部变形可以采用Peck的正态分布曲线描述;(2)涌水是造成隧道围岩发生严重坍塌的根本原因;(3)隧道破坏从拱顶开始,呈拱形破坏型式;(4)地表的两条主裂缝在隧道塌方初期形成,塌方对地表沉降和裂缝的主要影响区域位于两条主裂缝之间。
The construction of tunnels in water-rich, soft rock formations is prone to mudslides and landslides, which have a serious impact on the construction and surrounding environment. The surrounding rock of Beigang Tunnel is low in intensity and rich in groundwater. During the construction, the phenomenon of muddy water inundation has been encountered many times. There are serious disasters such as large-area collapse of surrounding rock, surface cracking and water table lowering. Taking Beigang tunnel as a prototype, an indoor model test was carried out, and the destruction of the tunnel was reappeared. The influencing factors, failure rules and scope of the tunnel collapse were studied. The results show that: (1) When no cracks occur on the ground surface, the surface deformation and internal deformation of the ground due to tunnel excavation can be described by Peck’s normal distribution curve; (2) Gushing water is the root cause of serious collapse of tunnel surrounding rock; (3) (4) The two main cracks on the surface form at the initial stage of the tunnel collapse, and the main impact area of the collapse on the surface subsidence and cracks is located between the two main fractures.