Excavation construction method of ultra-shallow buried uneven weathered stratum of tunnel

Abstract

The invention relates to an excavation construction method of an ultra-shallow buried uneven weathered stratum of a tunnel. A segmented step method is used for construction, and a tunnel section is divided into a left side of an upper station, a right side of the upper station, a middle station and a lower station; each segment of step is sequentially constructed circularly, one-time excavation length of each segment of step is not larger than 30m preferably, and a middle partition wall is changed into a straight wall from the traditional curved wall at the left side of the upper station. Thus, for the uneven weathered stratum in the shallow buried area of wall rocks, the dynamic construction method using the segmented step method has little process interference, reduces the construction cost, has simple operation, safety, reliability, less temporary support, low fund investment and high construction speed, is suitable for large machinery for construction, and ensures that the whole construction process is in a safe, stable, high-quality and high-speed controllable state.

Description

Technical field: [0001] The invention relates to a tunnel excavation construction method, in particular to an excavation construction method suitable for ultra-shallow buried uneven weathered strata. Background technique: [0002] The commonly used tunnel excavation methods include the double-side-wall pilot-pit method, the middle partition method, and the cross-middle partition method. The middle partition method is mainly used in the deep-buried hard rock sections of Class IV surrounding rocks of double-track tunnels and the old loess tunnels (Class IV surrounding rocks). The method of intersecting partitions is mainly used in the deeply buried soft rock, shallow buried and biased sections of Class IV surrounding rocks and deeply buried sections of Class V surrounding rocks. Therefore, neither of the two construction methods can be applied to the shallow buried section of V-level surrounding rock. Although the double-side-wall pilot pit method is mainly applied to the sh...

AI Technical Summary

Problems solved by technology

When the buried depth of the tunnel is only 6-21 meters, and the strata in the shallow buried section of the surrounding rock are mainly unevenly weathered strata of mudstone, argillaceous sandstone and sandy mudstone, due to the poor geology of this section: unevenly weathered red bed karst caves and Fissure cave water and karst are relatively developed, and the caves are mostly filled, and the scale of the caves is 1.0-5.2 meters; in addition, uneven weathered troughs and valleys are likely to cause collapse and instability, groundwater infiltration, etc. High safety risks and pressure on construction schedules

Moreover, the tunnel entrance is located in a deep foundation pit, and it is very difficult to enter the tunnel using the double-side-wall pilot pit rule.

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