Numerical Analysis of the Stability of Benlongping Tunnel Construction Plan

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 supporting 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 after 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.