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为确定无中导洞城市连拱隧道施工工法的适宜性,基于工程地质条件,采用数值模拟手段,研究了无中导洞连拱隧道开挖过程围岩竖向位移及隧道水平位移情况,对无中导洞连拱隧道围岩、衬砌结构等在不同开挖步时的力学特征以及隧道加强区受力机理进行分析,并模拟了加强区底部锚杆注浆及拱腰拱脚处搭设锁脚锚杆并注浆等加固措施。结果表明:隧道开挖后中部加强区隆起明显,这对于隧道中部加强区混凝土的稳定相当不利,应该采取控制隆起的措施;上台阶开挖时,拱脚处衬砌受力较大,宜将直角改为圆角以减小弯矩。开挖完成后,中部加强区底部的衬砌几乎处于纯弯状态,有必要提高该区域初衬厚度;对加强区底部岩体进行锚杆注浆加固的效果较好,能有效减少拱底隆起和初衬受力,同时对保持中部加强区混凝土的稳定也有较好的效果;在拱底和加强区底部搭设锁脚锚杆,特别是在加强区底部的锁脚锚杆对维持混凝土加强区的稳定有较大作用。
In order to determine the suitability of the construction method of double-arch tunnel without central guide tunnel, the vertical displacement of surrounding rock and the horizontal displacement of tunnel are studied by means of numerical simulation based on the engineering geological conditions. The mechanical characteristics of surrounding rock and lining structure of the tunnel without intermediate guide tunnel and the lining structure during different excavation steps are analyzed and the mechanism of stress in the tunnel reinforced area is analyzed. Foot bolt and grouting and other reinforcement measures. The results show that the rise of the central reinforced area is obvious after tunnel excavation, which is quite unfavorable to the stability of the concrete in the reinforced area of the central tunnel. Measures to control the uplift should be taken. When the upper step is excavated, Change to fillet to reduce bending moment. After excavation is completed, the lining at the bottom of the reinforced area in the central part is almost purely curved, so it is necessary to increase the thickness of the lining in the area. The effect of grouting reinforcement on the rock mass at the bottom of the reinforced area is better, which can effectively reduce the bulge and The initial lining of the force, at the same time to maintain the stability of the central reinforced area also have better results; in the bottom of the bottom and strengthening the area to build a lock bolt, especially in the bottom of the reinforced area of ?? the anchor bolt to maintain the reinforced area Stable has a greater effect.