Construction method for stability control of large-section tunnels crossing soil-rock boundary strata

Abstract

The invention discloses a large-section tunnel stability control construction method capable of passing through an earth and stone boundary stratum, and an earth and stone interface is positioned in an upper hole of a constructed tunnel. During excavation construction on the constructed channel, the large-section tunnel stability control construction method comprises the following steps: I, upperand middle step excavation step: performing upper and middle step excavation construction on the constructed tunnel in multiple excavation sections from rear to front, wherein the process of performing upper and middle step excavation construction on any excavation section comprises surveying and setting out, drilling and blasting construction, upper hole excavation and middle hole excavation; andII, lower step excavation construction. The large-section tunnel stability control construction method is reasonable in design, is simple and convenient in construction, is good in use effect, separately performs blasting region division on an upper blasting region in an upper step and a middle blasting region on a middle step, defines layout position of each blast hole in each blasting region, can effectively prevents tunnel face collapse or arch crown collapse caused by relatively great vibrations generated by blasting while large-section once explosive load is too great, ensures a safe andreliable tunnel excavation process, and can ensure a stable tunnel structure.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a construction method for controlling the stability of a large-section tunnel passing through an earth-rock boundary layer. 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 r...

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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