Method for constructing branch guide pits of tunnels

Abstract

The invention discloses a method for constructing branch guide pits of tunnels. The method includes steps of (1), carrying out preparation work; (2), constructing advanced pipe sheds and small guide pipes; (3), carrying out ring-type excavation on arches; (4), primarily supporting and temporarily supporting the arches; (5), excavating and supporting left and right guide pits; (6), excavating core soil and inverted arches; (7), primarily supporting the bottoms of the tunnels; (8), pouring and filling the inverted arches; (9), secondarily lining the tunnels. Compared with the prior art, the method for constructing the branch guide pits of the tunnels has the advantages that the arches of the large-span shallow-buried tunnels with fractured surrounding rock can be prevented from collapsing, and full construction procedures are in safe, stable and quick controllable states; the good rate of the engineering quality can reach 95% at least, and safety production accidents can be assuredly prevented.

Description

technical field [0001] The invention relates to a construction method, in particular to a construction method for tunnel subdivision pilot pits. Background technique [0002] my country has a vast territory with large surface undulations. About 75% of the land is mountainous or heavy hills, with an altitude difference of 5,000 meters. Most of the roads built in the 30 years after the founding of the People's Republic of China were winding around mountains or cutting slopes and digging deep, seriously damaging the ecological environment. Caused soil erosion and landslides, and even revived some ancient landslides. In the 1950s, there were only more than 30 road tunnels with a total length of 2,500 meters in my country. The construction has developed rapidly. During the "Ninth Five-Year Plan" period, 278,000 meters of new tunnels were built, and many extra-long tunnels were built, such as Zhongliangshan Tunnel, Jinyunshan Tunnel and Erlangshan Tunnel. With the in-depth developme...

AI Technical Summary

Problems solved by technology

The disadvantages of using the double-side-wall pilot-pit method are: 1. For shallow-buried long-span tunnels, especially in areas where the surrounding rock is relatively broken, the construction of the double-side-wall pilot-pit method is likely to cause problems such as the surrounding rock collapse and roof fall in the arch area of ​​the tunnel. High construction safety risks; 2. For biased tunnels, the horizontal displacement is relatively large; 3. Interaction between each process, slow construction speed

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