Method for excavating weak surrounding rock tunnel under water-rich high-ground-stress conditions

Abstract

The invention discloses a method for excavating a weak surrounding rock tunnel under water-rich high-ground-stress conditions. The method includes the following steps that firstly, advanced small pipe grouting and pre-supporting are carried out in advance before tunnel excavation; secondly, excavation is carried out according to a three-step seven-excavation-surface method; thirdly, C35 reinforced concrete is adopted in the secondary lining process, wherein the C35 reinforced concrete is 65cm in inverted arch thickness and 55cm in arch wall thickness and comprises phi22@20cm annular main ribs, phi14@20cm longitudinal steel ribs and phi8 stirrups. The method can effectively avoid the steel frame torsion and cracking phenomenon, thereby guaranteeing normal tunnel construction, accelerating construction and improving construction safety and engineering quality.

Description

Technical field: [0001] The invention belongs to a tunnel engineering construction method, in particular to an excavation method for weak surrounding rock tunnels under the condition of rich water and high ground stress. Background technique: [0002] For the weak surrounding rock under the condition of rich water and high ground stress, due to the complex geological structure, the excavation of the surrounding rock is easy to collapse, the rock mass is broken, and the compressive strength is reduced, so the rock mass is very easy to collapse, threatening the safety of construction personnel. After the initial support is completed, the surrounding rock has almost no self-stabilization ability, and the initial support body has a huge bearing capacity, which is easy to cause the steel frame to be twisted, deformed, broken, and intruded into the secondary lining, etc., which seriously affects the construction safety, construction quality and construction progress. [0003] Soft...

AI Technical Summary

Problems solved by technology

[0002] For the weak surrounding rock under the condition of rich water and high ground stress, due to the complex geological structure, the excavation of the surrounding rock is easy to collapse, the rock mass is broken, and the compressive strength is reduced, so the rock mass is very easy to collapse, threatening the safety of construction personnel

After the initial support is completed, the surrounding rock has almost no self-stabilization ability, and the initial support body has a huge bearing capacity, which may easily cause the steel frame to be twisted, deformed, broken, and intruded into the secondary lining, etc., which seriously affects the construction safety, construction quality, and construction progress.

[0003] Soft rock tunnels are relatively common at home and abroad, but the practicability of the soft rock deformation control construction method and the versatility of the complete set of technologies are still insufficient. The guidance and reference of the construction technical documents are greater than the actual application in engineering. In particular, the experience and technical basis for the construction of large-section soft rock tunnels under high ground stress and water-rich conditions are even more lacking.

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