奔龙坪隧道施工方案稳定性数值分析

Numerical Analysis of the Stability of Benlongping Tunnel Construction Plan

连拱隧道在左右洞施工时,边开挖边支护,围岩和支护结构之间的荷载转换频繁,而且目前连拱隧道的开挖多采用钻爆法,爆破施工对中隔墙及顶部围岩的扰动大。因此,结合隧道地质条件选择安全、可行的施工开挖方案意义重大。以在建的奔龙坪隧道为工程背景,采用数值模拟方法,就隧道施工中右幅正洞和左幅正洞的施工顺序进行系统的模拟分析,确定了隧道中导洞开挖其后进行右幅正洞开挖,在右幅正洞贯通后再施工左幅正洞的施工方案,指导该隧道的施工。

When the double-arch tunnel is under construction on both holes , the excavation is always followed by the construction of the supporting structure ,which leads to frequent load transfer between the surrounding rocks and the sup-porting structure .Furthermore ,because drilling and blasting method is widely adopted in the excavation of double-arch tunnels ,the disturbance caused by the blasting to the mid-partition wall and top surrounding rocks is large .Therefore ,it is of great importance to choose a safe and reliable excavation program ,according to the practical geological conditions of the tunnel .Here ,based on the on-going construction of Benlongping tunnel ,numerical simulation was adopted to analyze the construction sequence of the right and left holes .The conclusion is drawn that the right tunnel should be excavated af-ter the pilot hole is constructed ,the left tunnel should be constructed when the right tunnel is fully finished .This result will guide the construction of the above -mentioned tunnel .