软岩隧道衬砌内力计算与开挖过程数值模拟

Calculation of Lining Internal Force and Numerical Simulation of Excavation Process of a Soft Rock Tunnel

为完成软岩隧道衬砌结构设计,需对隧道围岩压力及二衬内力进行计算,同时需对施工过程稳定性进行分析。二衬内力计算分别采用辛普生法和荷载结构法进行,采用有限差分软件对隧道施工过程围岩应力、应变变化规律进行分析,找出围岩受力最不利位置,并对其进行动态监测。经过计算,拱脚处二衬轴力分别为657.55 kN、633.48 kN,弯矩分别为55.90 kN·m、46.97 kN·m,轴力相差较小,而弯矩相差稍大。通过施工过程数值模拟分析发现拱底发生底鼓现象,在隧道两侧拱腰、拱顶、拱底先后出现应力集中现象,可在实际施工过程中采取相应加固措施。

In order to complete the lining structure design of soft rock tunnel, it is necessary to calculate the surrounding rock pressure and the internal force of the second lining, and analyze the stability of the construction process. The internal force of the second lining is calculated by using Simpson method and load structure method respectively. The finite difference software is used to analyze the stress and strain changes of surrounding rock during the tunnel construction process, find out the most unfavorable position of surrounding rock, and carry on dynamic monitoring to these positions. After calculation, the calculated results of the internal force of the second lining at the arch foot are 657.55 kN and 633.48 kN, and the bending moment is 55.90 kN·m and 46.97 kN·m, respectively. The difference of the axial force is small, but the difference of the bending moment is slightly larger. Through the numerical simulation analysis of the construction process, it was found that the heave phenomenon occurred at the bottom of the arch, and the stress concentration phenomenon successively appeared at the waist of the arch, the vault and the bottom of the arch on both sides of the tunnel. The corresponding reinforcement measures can be taken in the actual construction.