山岭隧道Ⅳ级围岩不同应力释放率下施作二衬规律

依据在建的延崇高速杏林堡隧道工程地质条件,借助FLAC3D有限差分软件,采用Hoek-Brown屈服准则,对五种埋深条件下Ⅳ级围岩不同应力释放率下施作二衬进行了数值模拟。通过分析围岩特征点位移、二衬应力和围岩应力后得出结论:同一埋深条件下,围岩应力释放率对围岩位移影响不大,随着埋深加大,围岩位移和二衬应力呈倍数增长趋势;围岩释放率为70%～90%时为最佳支护二衬时机,此时初支承受荷载比二衬大,能充分发挥围岩自承能力;拱脚部位岩体存在应力集中,拱腰受水平应力影响较大,并随埋深的加大二者现象越明显,需对它们加强支护。

Study on the Law of Constructing Second Lining under Different Stress Release Rates of Class IV Surrounding Rocks in Mountain Tunnel

According to the engineering geological conditions of the Yanchong high-speed Xinglinbao Tunnel under construction, using the FLAC3D finite difference software, the Hoek-Brown yield criterion is adopted,numerical simulation of the application of secondary lining under different stress release rates of grade IV surrounding rock under five buried depth conditions.By analyzing the displacement of characteristic points of surrounding rock, the stress of surrounding lining and the stress of surrounding rock, it is concluded that the stress release rate of surrounding rock has little effect on the displacement of surrounding rock under the condition of the same buried depth. With the increase of buried depth, the displacement of surrounding rock and the stress of secondary lining are multiplied. When the release rate of the surrounding rock is 70%~90%, it is the best time to support the second lining. At this time, the initial support is larger than the secondary lining load, and the self-supporting ability of the surrounding rock can be fully exerted. There is stress concentration in the rock mass of the arch foot, the arch waist is greatly affected by the horizontal stress, and the phenomenon is more obvious with the increase of the buried depth, It is necessary to strengthen the support for them.