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以某砂岩隧道为背景,首先应用弹塑性理论对隧道开挖后围岩的变形屈服和拱顶及边墙的应力状态进行了分析,继而采用有限差分软件FLAC3D模拟了隧道开挖过程中围岩的位移及塑性变形情况。计算结果表明:该研究段隧道发生塑性屈服的临界深度为78.2m;当隧道开挖31m后,由于开挖卸荷作用使得原先储存在围岩内的大部分应力得以释放,此后围岩变形基本趋于稳定;该隧道在开挖过程中,边墙变形量最大,达到1.94mm,由于隧道在开挖过程中围岩的自稳作用,当开挖到一定时间后,围岩变形将趋于稳定;该隧道在开挖过程中,拱顶和底部以拉张破坏为主,边墙则产生剪切破坏。
Based on a sandstone tunnel, the deformation yielding of the surrounding rock after tunnel excavation and the stress state of the vault and sidewall were analyzed by using the elasto-plastic theory. Then the finite difference software FLAC3D was used to simulate the surrounding rock The displacement and plastic deformation. The calculated results show that the critical depth of plastic yielding in the tunnel is 78.2 m. After 31 m of tunnel excavation, most of the stress previously stored in the surrounding rock is released due to excavation and unloading, Tends to be stable. During the excavation process, the deformation of the side wall is the largest, reaching 1.94mm. Due to the self-stabilization of the surrounding rock during the tunnel excavation, the deformation of the surrounding rock will tend to be larger after excavation for a certain period of time In the process of excavation, the vault and the bottom of the tunnel are mainly tensioned and damaged, while the sidewalls are sheared and damaged.