中文摘要：

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。

英文摘要：

Tunneling in saturated soft rocks may induce serious environment problems. During the excavation of Beigang Tunnel, a railway tunnel in soft rock mass rich in water, a large volume of water and soil flowed into the tunnel and induced severe damage at several sites. At these sites, water table fell down, ground surface cracks occurred. Taking Beigang Tunnel as the prototype, model tests are conducted to study the pattern and law of ground subsidence and cracks when tunneling in soft rock with high water content. It was found that： （1） The transverse settlements curve of ground before collapse can be well described by the normal probability curve proposed by peck. （2） Water and soil flow is the main reason for severe damage in Beigang Tunnel. （3） Collapse happens firstly at the top of the tunnel and then develops upwards to form an arch shaped failure structure. （4） Main influenced area on surface by tunneling is limited in the region between the two largest cracks, which come into being in the early stage of collapse and located on the each side of the tunnel axis respectively.