中文摘要：

针对软弱岩体中隧道开挖过程中出现的塌方破坏问题,通过室内地质力学模型试验和数值模拟,对有、无锚杆支护情况下围岩的渐进性破坏过程、岩体地表变形以及岩体内部的应力变化规律进行了对比分析,所得结论如下所述：①隧道开挖使得上覆岩层荷载向隧洞左、右两侧转移,拱腰以下岩体往往率先剪切破坏,锁脚锚杆可有效制止岩体初始剪切破坏;②围岩破坏自洞周逐渐向岩体深部发展,沿与水平面夹角为45°＋φ/2的方向产生两个滑动面,并在洞顶形成一自然平衡拱,锚杆支护可有效减小岩体塌落范围;③锚杆的存在大大改善了围岩的应力状态,不仅提高了拱腰岩体剪切起裂荷载值,而且还使得拱顶岩体在破坏前可承担更大的上覆荷载;④塌落区内的岩体切向应力呈＂跌落式＂下降,此特征可用于判断岩体塌落范围及为隧道塌方预警服务。

英文摘要：

In view of the collapse accidents encountered in the process of tunneling in weak and fractured rock mass, scaled model tests and numerical simulations are developed to study the progressive failure process of surrounding rock mass as well as the characteristics of ground surface deformation and stress of rock mass under different bolt support modes. According to the results, the following conclusions can be drawn：（1） Tunnel excavation may cause the overburden load to transfer from the crown to the both side walls, resulting in the shear failure of rock mass below tunnel waist, therefore, the foot lock bolts can be used to halt this initial failure.（2） The failure of rock mass mostly starts from the tunnel periphery and then develops gradually outwards, which eventually leads to the emergence of two sliding surfaces appeared with an angle of 45°＋φ/2 to the horizontal plane and a natural equilibrium arch formed above the tunnel arch, and the bolt support can effectively reduce this collapsed region.（3） Due to the improvement of stress state in surrounding rock mass, bolt support not only increase shear strength value of rock mass at the tunnel waist but also make the rock mass above tunnel crown bear even larger overburden load before completely failure.（4） The tangential stress of rock mass within the collapsed region drops down sharply, and this feature can be used to determine the collapse range of rock mass and is also regarded as the early warning signal for tunnel collapse.