不良地质引水隧洞开挖支护应力变形数值模拟研究

Numerical simulation research on the unfavorable geological diversion tunnel excavation support stress deformation

选取围岩强度低、变形量大的不良地质段为代表断面进行计算分析,建立了FLAC3D模型,研究隧洞开挖支护围岩的变应力变形情况。结果表明:隧洞的开挖破坏了围岩的原始应力场,隧洞径向轴力释放,切向应力集中,隧洞顶拱位置形成了比较明显的开挖松动圈。隧洞支护后,支护措施承受部分围岩压力,围岩应力得到改善,隧洞围岩变形明显减小,开挖断面变形整体趋于均匀,隧洞周边塑性区有所改善,因此支护措施对围岩变形起明显的限制作用。

The unfavorable geological section with low strength and large deformation of the surrounding rock was selected as the representative section for the calculation and analysis, and the FLAC3D model was used to study the deformation and stress of surrounding rock of tunnel excavation support.The results show that tunnel excavation destroy the original stress field of surrounding rock, the radial axial force of the tunnel releases, tangential stress concentrates, t and the tunnel top arch position forms an obvious excavation loop.After the tunnel supporting measures, the supporting measures bear some of the surrounding rock pressure, the surrounding rock stress is improved, the tunnel surrounding rock deformation is obviously reduced, the overall deformation of excavation section tends to be uniform, and the plastic zone around the tunnel has been improved.Therefore, the supporting measures have restrict effect on the deformation of surrounding rock.