Abstract: Deep-buried soft rock hydraulic tunnel is faced with the extrusion deformation of high stress surrounding rock. The excavation construction is extremely difficult, and the later operation environment and working conditions are complex. Therefore, the safety and stability in the whole construction process and the long-term operation stage must be taken into consideration in the excavation and support design. Taking a deep-buried soft rock hydraulic tunnel as the research object, the anisotropic mechanical properties of the soft rock are investigated, and the layout scheme, systematic support design, blasting excavation control and other aspects are discussed. To avoid the adverse effects of schist anisotropy, the axis of the tunnel is recommended to be N4°W. To deal with the large deformation of soft rock, the convergence strain rate of 3%~5% is suggested as the deformation control standard of the surrounding rock. Based on the modern supporting principle of surrounding rock, the dynamic and progressive supporting method ——"sequential application, first soft and then rigid, multi-step control" is proposed to control the significant compression deformation of surrounding rock. The concept in deep-buried soft rock hydraulic tunnel support design that the surrounding rock is the main body to bear the load and to prevent seepage is always adhered to. The relevant research results can provide important reference for the construction of similar projects.

Key words: deep-buried soft rock, hydraulic tunnel, schist anisotropy, engineering countermeasures

摘要： 深埋软岩水工隧洞面临突出的高应力围岩挤压变形问题，开挖施工难度极大，后期运行环境及工况复杂，其开挖支护设计须统筹兼顾施工全过程及长期运行的安全稳定性。以某深埋软岩水工隧洞为研究对象，考察了该类软岩的各向异性力学特性，并对隧洞布置方案、系统支护设计、爆破开挖控制等方面进行了论述。其中，为规避片岩各向异性的不利影响，推荐洞轴线的走向为N4°W；为应对软岩挤压大变形问题，建议采用3%~5%的收敛应变率作为围岩的变形控制标准；依托现代围岩支护原理，提出采用“逐次施加、先柔后刚、多步控制”动态渐进支护方式来调控围岩显著挤压变形问题，并始终秉承围岩是隧洞承载和防渗的主体的深埋软岩水工隧洞支护设计理念。相关研究成果可为同类工程建设提供参考。

关键词: 深埋软岩, 水工隧洞, 片岩各向异性, 工程对策