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兰海高速公路麻崖子隧道位于西秦岭山区,围岩破碎,埋深较大,地应力较大,施工中存在较大安全隐患。对隧道围岩内部位移、锚杆轴力、支护钢拱架内力、围岩与锚喷混凝土接触压力、岩隙涌水量等进行现场监测,并结合地质勘查资料进行了综合分析。结果表明:隧道开挖后围岩产生较大变形,未支护围岩在施工爆破中容易产生岩体塌落事故,提出利用超前地质预报及时掌握掌子面围岩和地层的情况,并根据围岩状态变换爆破方法,在初期支护前喷上一层纤维混凝土以增加破碎岩体的胶结力等措施。
Lanya Expressway Maoyazi Tunnel is located in the western Qinling Mountains, surrounding rock broken, larger depth, greater stress, there is a big security risk in construction. The internal displacement of tunnel surrounding rock, the axial force of anchor rod, the internal force of supporting steel arch, the contact pressure between surrounding rock and anchor shotcrete, the water influx of rock crevices and so on were monitored on site, and the comprehensive analysis was carried out based on the geological survey data. The results show that large deformation of surrounding rock occurs after tunnel excavation, and the unsupported surrounding rock is prone to rock mass collapse accident during construction blasting. It is proposed that the use of advanced geological prediction can timely grasp the surrounding rock and formation of the face and according to Surrounding rock state transformation blasting method, before the initial support sprayed with a layer of fiber reinforced concrete to increase the cementation strength of broken rock and other measures.