小净距隧道施工工序的数值模拟分析

Numerical Simulation of Construction Process of Tunnel with Small Clear Distance

结合干田冲隧道工程项目,采用FLAC3D数值模拟分析了不同施工工艺下该Ⅳ级浅埋偏压小净距隧道中夹岩柱应力应变特性及其稳定性,探讨了小净距隧道合理施工工艺、控制围岩稳定、施工质量和安全的措施。结果表明:施工工艺会对浅埋偏压小净距隧道的中夹岩柱稳定性产生不利影响。相对先行洞全断面法后行洞上下台阶法、先行洞上下台阶法后行洞全断面法及全断面法而言,上下台阶法施工对中夹岩柱稳定性扰动最小,建议该小净距隧道采用上下台阶法施工以保证隧道施工质量与安全。

Combining with the Gantianchong Tunnel project which is a Grade IV shallow embedded bias tunnel with small clear distance, using the FLAC3D numerical simulation, stress and strain characteristics and stability of the middle rock pillar are analyzed under different construction techniques, and methods to control surrounding rock stability and the construction quality and safety measures are discussed. The results show that construction process will have an adverse effect on the stability of rock pillars. Relatively full face method after existing tunnel ~ benching tunneling method of following tunnel, benching tunneling method after existing tunnel ~ full face method of following tunnel and full face method for benching tunneling method in the construction of the middle rock pillars stability with minimum disturbance. It is recommended that the shallow embedded bias tunnels with small clear distance construction adopt the benching tunneling method in order to ensure the quality and construction safety.