Quick sealing method for excavating phyllite stratum tunnel

Abstract

The invention discloses a quick sealing method for excavating a phyllite stratum tunnel. The method comprises four steps, wherein a tunnel face is subjected to advanced small conduit grouting supporting before being excavated in the step (1); grouting anchor rods with lengths L of more than or equal to 8m are adopted as foot locking anchor rods of steel frames of each step in the step (2); surrounding rocks behind primary supports are subjected to grouting reinforcement after the primary supporting of each step; in each excavation cycle in the step (4), the excavation length of the upper step is 1 frame, the middle step is 2 to 3 frames, the lower step is 2 to 3 frames, and the tunnel bottom is 4 to 6m. According to the excavation method, the excavation lengths of the middle and lower steps and the tunnel bottom in each cycle are increased under the condition of no changes in the footage of the upper step in each cycle, the primary supporting closing time is shortened, the deformation of the tunnel is effectively controlled, the engineering cost is greatly lowered, the construction safety is ensured, the construction progress is accelerated, and the method is easy to operate, and has higher popularization and application value.

Description

Technical field: [0001] The invention belongs to a tunnel construction method, in particular to a fast sealing method for tunnel excavation in phyllite formation. Background technique: [0002] For large-section phyllite tunnels, the more common excavation methods include step method, short step method, three-step seven-step method, CD method, CRD method, and side wall pilot pit method. Too many, or each time the footage is small, it takes too long to close the entire section of the initial support of the tunnel to form a loop, which not only easily produces large deformation, but also affects the construction progress and safety. In the construction process of the three-step seven-step method, the excavation length of the middle and lower steps generally does not exceed 2 meters, and the excavation length of the inverted arch generally does not exceed 3 meters. The construction speed is slow and the initial support closure time is long. Invention content: [0003] The pu...

AI Technical Summary

Problems solved by technology

[0002] For large-section phyllite tunnels, the more common excavation methods include step method, short step method, three-step seven-step method, CD method, CRD method, and side wall pilot pit method. If there are too many, or each time the footage is small, it will take too long for the entire section of the initial support to be closed and formed into a ring, which will not only easily cause large deformation, but also affect the construction progress and safety.

In the construction process of the three-step seven-step method, the excavation length of the middle and lower steps generally does not exceed 2 m, and the excavation length of the inverted arch generally does not exceed 3 m, the construction speed is slow, and the closure time of the initial support is long

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