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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。
Aiming at the problem of landslide damage in the process of tunnel excavation in soft rock mass, through the indoor geomechanical model test and numerical simulation, the gradual failure process of rock mass with or without rock bolt support, surface deformation of rock mass and rock The internal stress changes are compared and analyzed. The conclusions are as follows: ① Tunnel excavation makes the overburden load transfer to the left and right sides of the tunnel, and the rock mass below the arch waist is the first to shear failure. Which can effectively prevent the initial shear failure of the rock mass. ②The surrounding rock failure gradually develops from the cave to the deep of the rock mass, and two sliding surfaces are generated along the direction of the 45 ° + φ / 2 angle with the horizontal plane and form a Natural balance arch and bolt support can effectively reduce the rock mass collapse range; (3) The existence of anchor rod greatly improves the stress state of surrounding rock, which not only improves the shearing and rupturing load value of arch and waist rock mass, but also makes the arch The top rock mass can bear a greater overburden before failure; (4) the tangential stress of the rock mass in the caving area is “drop-in-type”, which can be used to judge the range of rock mass collapse and pre-warning the tunnel collapse service.