Pre-reinforcement and Excavation Construction Method for Tunnel Crossing Earth-rock Boundary Strata

Abstract

The invention discloses a tunnel pre-reinforcement and excavation construction method crossing the earth-rock boundary stratum, comprising the following steps: 1. Pre-reinforcement by precipitation; 2. Excavation construction of the rear tunnel section; 3. Excavation construction of the middle tunnel section; 4. 1. The excavation construction of the front tunnel section; the middle tunnel section and the front tunnel section are all three-step synchronous excavation tunnel sections; in step 2, step 3 and step 4, the excavation process is carried out from back to front, Simultaneously carry out initial support for the excavated tunnel hole from back to front. The invention is reasonable in design, easy in construction and good in use effect. Firstly, the underground water level is lowered through precipitation pre-reinforcement and the surrounding rock is effectively reinforced, and then a suitable drilling and blasting method is selected according to the positional relationship between the soil-rock interface and the tunnel hole, and three steps are adopted. The simultaneous excavation method for blasting excavation can ensure the safety and reliability of the excavation process of the tunnel passing through the soil-rock boundary stratum, and can ensure the stability of the tunnel structure.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a tunnel pre-reinforcement and excavation construction method for crossing soil-rock boundary strata. Background technique [0002] In the construction process of railway and highway tunnel projects, due to the limitation and influence of geological conditions, it will cause great influence and difficulties to the construction during the construction process. In the process of tunnel construction, various combinations of rock formations are often encountered, such as weak and uneven surrounding rock, shallow buried bias landform, soil-rock mixed geology and so on. For the excavation and support of tunnels that pass through soil-rock mixed strata (also known as soil-rock interface geology or soil-rock boundary strata), at present, the main methods in China are advanced pipe shed grouting support, advanced horizontal jet grouting pile reinforcement, and cont...

AI Technical Summary

Problems solved by technology

During the actual tunnel construction, the main problems of tunnel excavation in the soil-rock boundary stratum are as follows: first, the hardness of the rock and soil is not uniform, and the blasting of the weathered rock layer in the lower part will easily cause the upper soil layer to collapse, which is harmful to the construction personnel; second, the groundwater The enrichment area further softens the soil-rock boundary strata, causing serious deformation of the surrounding rock; third, the swelling of the expansive soil with water causes the primary support to deform and crack, and in severe cases, the deformed structure of the primary support arch will be damaged and the support capacity will be lost

Once the corresponding reasonable support measures are not adopted in the actual construction or the excavation method is improper, it is very likely to cause deformation of the support in front of the face of the tunnel, and even serious consequences of collapse

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