[Objective] In the excavation process of layered rock tunnel under high stress environment, the spatiotemporal evolution law of surrounding rock fracture zone and its stability control constitutes a key scientific challenge in deep engineering. [Methods] The dynamic development process of surrounding rock fracture zone after excavation of Danba layered rock diversion tunnel under high ground stress and its temporal and spatial evolution law affected by stress environment are systematically studied by means of theoretical analysis and numerical simulation. [Results] Firstly, based on the relationship between the bedding occurrence of layered rock mass and the tunnel axis with three-dimensional ground stress, the mechanical mechanism of asymmetric fracture of oblique layered tunnel with large dip angle is analyzed. The expansion range, morphological evolution and stress redistribution law of the surrounding rock damage and fracture zone during tunnel excavation are systematically simulated, and the non-uniform expansion of the fracture zone in space and the staged evolution characteristics in time with the excavation process are revealed, by establishing a three-dimensional numerical model. [Conclusion] On this basis, a control method with stress optimization as the core is proposed, including the optimization of excavation method and the adjustment of support scheme, meanwhile its effectiveness and applicability are verified by numerical simulation. Finally, the excavation and support scheme is designed as three-bench excavation. The heights of the upper, middle and lower steps are 3 m, 5 m and 7 m respectively. The support scheme is to use 8 m long bolt, the spacing between rows is 1.5 × 1.5 m, and the plum-shaped arrangement is close to the working face as much as possible. The research results provide theoretical basis and method support for stability control and safe construction of high stress layered rock tunnel engineering.
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