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在城市化进程中经常需要对山坡进行整平,对沟谷、边坡进行填平,随着城市规模的发展,面对回填土工程问题越来越多。基于此,针对重庆轨道交通某线路所涉及的回填土地层,对回填土的力学特性进行了试验研究,并对穿越回填土区隧道的开挖方案进行了对比分析。研究结果表明:隧道衬砌内力最大值并不一定发生在最终开挖完成后;同核心土法相比,台阶法开挖时隧道围岩变形较大,水平变形提高达74.80%,竖向变形19.39%,纵向变形42.39%,核心土法能有效控制围岩变形。不同开挖方法下隧道围岩应力差异较大,但最终围岩应力值差异性小,表明围岩应力与最终开挖状态密切有关;衬砌内力变化较大,预留核心法下轴力减小20%,弯矩减小217%,这表明预留核心土法能有效降低衬砌内力,从而提高衬砌承载力。
In the process of urbanization, it is often necessary to level the hillsides and fill the valleys and slopes. As the size of the city grows, more and more problems are encountered in the backfill project. Based on this, aiming at the backfill soil layer involved in a line of Chongqing rail transit, the mechanical properties of the backfill soil were studied and the excavation schemes of the tunnels crossing the backfill area were comparatively analyzed. The results show that the maximum internal force of tunnel lining does not necessarily occur after the completion of the final excavation. Compared with the core soil method, the deformation of the surrounding rock of the tunnel is large when the step method is used for excavation. The horizontal deformation increases by 74.80% and the vertical deformation by 19.39% , Longitudinal deformation 42.39%, core soil method can effectively control the deformation of surrounding rock. However, the difference of surrounding rock stress is small, which indicates that the stress of surrounding rock is closely related to the final excavation status. The variation of internal force of lining is relatively large, and the axial force under the core set method is reduced 20% and the bending moment is reduced by 217%, which shows that reserving the core soil method can effectively reduce the lining internal force and improve the lining bearing capacity.