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针对雷公浦小净距隧道后行左洞洞口段具有半硬岩层半软岩层的特点,在开挖过程中,按照新奥法对隧道地表沉降、拱顶下沉、水平收敛、中间岩柱的位移、锚杆轴力、围岩压力和钢拱架应力等项目进行监测。监测结果表明,采用预留核心土法可以较好地控制围岩变形和应力;后行洞的拱顶沉降大于先行洞,且软岩一侧的下沉量更大;中间岩柱较薄弱,开挖初期往先行洞方向移动;降雨对围岩变形和压力影响较大,施工中应引起重视。研究结论可为类似条件下工程的设计、施工和监测提供借鉴。
In view of the characteristics of semi-hard rock semi-soft rock formation at the left-end of the tunnel after the small clear distance tunnel of Leigu Pu tunnel, during the excavation process, according to the new Austrian method, the tunnel surface settlement, vault settlement, horizontal convergence, Displacement, anchor axial force, surrounding rock pressure and steel arch stress and other projects to monitor. The monitoring results show that the deformation and stress of the surrounding rock can be well controlled by using the reserved core soil method. The settlement of the vault of the backward tunnel is larger than that of the pilot tunnel and the sinking amount of the soft rock is greater. The middle rock column is weak, In the early excavation, it moves toward the first hole; rainfall has a great influence on deformation and pressure of surrounding rock, and should be paid attention to during construction. The conclusions can provide reference for the design, construction and monitoring of the project under similar conditions.