深部复合地层TBM隧道围岩应力与变形规律模型试验研究

Experimental investigation on surrounding rock stress and deformation rule of TBM tunneling in deep mixed strata

为研究深部复合地层TBM隧道有、无支护条件下围岩应力变形破裂与地层效应之间的关系,采用自行研制的双轴平面应变相似模型试验系统,运用应力、应变量测装置及自主开发的精细化岩土数字照相量测系统PhotoInfor,对深部复合地层TBM隧道进行了试验研究。结果表明:上软下硬地层中,应力分布不均,硬岩部分应力较大,变形破裂的模式差异大,不均匀性明显,地层效应显著;有、无支护条件下围岩内部应力随围压增大而增大,且沿洞径方向呈先增后减的变化趋势;再现了无支护条件下围岩变形破裂及松动圈发展全过程,上部软岩以坍塌为主,下部硬岩以破裂为主;获得了硐周岩体径向位移发展阶段;支护结构可有效改善围岩应力重分布情况、减缓围岩卸载速度,提高围岩的自承载能力和隧道的整体稳定性。

In order to investigate the stress,deformation,and stratigraphic effects of surrounding rock between the supported and unsupported TBM tunnels in deep mixed strata,an experimental investigation was conducted by a self-developed biaxial plane strain similarity model test system.The stress-strain measurement devices and the self-developed refinement digital photogrammetric measurement system named PhotoInfor were applied in this study.The results show that the stress distribution and failure mode are distinctly different between the upper-soft and lower-hard strata,showing an obvious non-uniformity stratigraphic effect.The stress in hard rock is larger than that in soft rock.As the confining pressure increases,the internal stress of surrounding rock firstly increases and then decreases along the radial direction for both supported and unsupported tunnels;under the unsupported condition,the evolution of the deformation and failure process and the broken rock zone of the surrounding rock have been fully investigated.The upper-soft rock is dominated by collapse,while the lower-hard rock is dominated by fracture.The development stages of radial displacement for surrounding rock is also summarized;the supporting structures effectively improve the stress redistribution and the integrity of surrounding rock,slow down the unloading speed and enhance the self-bearing capacity of surrounding rock.