Bilateral expanding excavation construction method for middle pilot tunnel in tunnel

Through the double-side expansion construction method of the central guide tunnel, the step method construction and the "load-structure" model calculation are used to solve the initial support closure and support connection problems in the double-side wall guide tunnel method, and improve the safety of tunnel construction. stability and progress, reducing the impact of surrounding rock deformation.

CN109611100AActive Publication Date: 2019-04-12CHINA RAILWAY 12TH BUREAU GRP CO LTD +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
CHINA RAILWAY 12TH BUREAU GRP CO LTD
Filing Date
2018-11-20
Publication Date
2019-04-12

AI Technical Summary

Technical Problem

The existing double-side wall guide pit method has problems such as the initial support being unable to be closed during tunnel construction, the support on both sides not being connected to the vault support, and the bottom of the side wall being suspended during invert excavation, which leads to potential quality and safety hazards. The progress is also slow and difficult to meet modern construction needs.

Method used

The construction method of double-sided expansion of the central pilot tunnel is adopted. The central pilot tunnel is constructed using the step method. The initial support distance from the tunnel face is no more than 1.5 times the excavation width. The excavation width of the side tunnel meets the space requirements for anchor rods and shipping machinery. The side tunnel The initial support closure distance shall not exceed the excavation width of the middle tunnel, and the support load shall be determined through "load-structure" model calculation to ensure the stability and progress of the support structure.

Benefits of technology

The initial support of the central guide tunnel was closed in time, and the side tunnel support and the central guide tunnel support were connected in sequence, which reduced the impact of surrounding rock deformation. The construction progress was close to that of ordinary two-lane or two-lane tunnels, which improved construction safety and efficiency.

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Abstract

A bilateral expanding excavation construction method for a middle pilot tunnel of a tunnel is provided. Section or excavation width of the middle pilot tunnel is generally not larger than that of a common double-line or double-lane tunnel; a step construction method is adopted, and the construction method is the same as that of a common double-line or double-lane tunnel; and the construction method is familiar to constructors, and the construction difficulty is avoided. A primary support section of the middle pilot tunnel can be expanded and excavated after being closed by at least 3 meters; if a side tunnel face is stable, and the problem of the operation height of manual installation of a steel frame and an anchor rod is solved, one-time excavation and support can be achieved, and the construction is more convenient; or otherwise, a side tunnel is excavated according to a two-step or three-step method. The primary support of the middle pilot tunnel can be timely closed; the primary support of the side tunnel and the primary support of the middle pilot tunnel can be completely connected in sequence, and various errors and deformation influences of surrounding rocks and the supportare left at an inverted arch part for treatment; and the construction progress is basically the same as that of the common double-line or double-lane tunnel.
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