断层特征与掘进方法对隧道围岩稳定性影响分析

Analysis of influence of fault characteristics and tunnel excavation method on stability of surrounding rock

以都昌至九江高速公路温泉隧道为工程背景,采用有限元方法对隧道穿越不同断层倾角、隧道与断层相对位置、隧道不同开挖方法等情况下围岩的稳定性进行了模拟计算分析。结果表明和无断层情况相比较,断层的存在使得围岩的整体位移增加,拱顶沉降增加约18.3%,仰拱隆起增加约35.1%,围岩位移最大区域向垂直于断层方向偏移,不再具有对称性;断层位于隧道拱肩处时拱顶沉降量最大,断层位于隧道拱脚时,对围岩拱顶沉降量的影响最小,围岩最为稳定;采用上下台阶法进行开挖其拱顶位移量要比采用侧壁导坑法开挖所产生的位移量大77.04%,仰拱隆起量大60.3%;断层倾角为45°时,隧道开挖时围岩相对比较稳定。

The Wenquan tunnel from Duchang to Jiujiang was taken as the engineering background in this paper. The stability of surrounding rock was simulated and analyzed with the method of finite elementsin different cases, namely, tunnel passing through different dip angle faults, the relative position of tunnel and fault, and the excavation method of tunnel The results show that the total displacement of the surrounding rock is increased by the fault, and the settlement of the vault increases by about 18.3 %, and the heave of the invert is about 35.1%. The biggest displacement zone of surrounding rock shifts to the direction of the fault direction and it no longer has symmetry. When the fault is located in the shoulder of the tunnel, the arch crown settlement is the maximum;while the fault is located in the foot of tunnel, the impact on the arch crown settlement is the smallest. The vault displacement of the upper step method is about 77.04% more than that of the side heading method and the amount of inverted arch is about 60.3 %. When the dip angle of the fault is 45 degrees, the surrounding rock of tunnel is relatively stable.