Construction method for soft surrounding rock section of large-span tunnel portal

A construction method and a technology for weak surrounding rocks, applied in tunnels, tunnel linings, earthwork drilling and mining, etc., can solve problems such as large convergence around, slow construction progress, large vault sinking, etc., to reduce convergence deformation and avoid passive impact force effect
CN102071947BActive Publication Date: 2013-02-06THE FIRST ENG OF CCCC FOURTH HARBOR ENG
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
THE FIRST ENG OF CCCC FOURTH HARBOR ENG
Publication Date
2013-02-06

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Abstract

The invention discloses a construction method for a soft surrounding rock section of a large-span tunnel portal. The construction method comprises the following steps of: excavating an arc-shaped pilot tunnel on the top of a tunnel section; performing initial support in time after the excavation process is finished and performing temporary support at the same time; excavating upper pilot tunnels on the left side wall and the right side wall at the same time; performing initial support in time after the excavation process is finished and performing temporary support on the core soil side walls at the same time; excavating lower pilot tunnels on the left side wall and the right side wall at the same time, wherein the depth of circulation drilling for each time is 0.5 m; performing initial support in time after the excavation process is finished and performing temporary support on the lower parts of the core soil side walls at the same time; performing large core soil excavation; reserving core soil steps; installing inverted arch steel frames and injecting C25 concrete in time, so that the initial support of the whole tunnel forms a closed ring as soon as possible; and dismantling the temporary support. By the top arc side wall pilot tunnel construction method, vault subsidence can be favorably controlled; and the method is applicable to tunneling excavation construction for strongly differentiating a surrounding rock portal when the tunnel portal is under the protection of a large pipe roof section.
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Description

technical field

[0001] The invention relates to the technical field of tunnel construction, in particular to the technical field of tunnel opening construction. Background technique

[0002] The construction of the tunnel entrance section has always been a difficult point in tunnel construction. With the rapid development of my country's highway industry, there are more and more large-section tunnels with three or four lanes in highway tunnels, and the increase in tunnel section increases the difficulty of tunnel construction. In addition, most The tunnel has the characteristics of weak surrounding rock, complex geology, shallow burial, and partial pressure, making the construction of the tunnel more difficult. Due to poor cave-forming conditions, the surrounding rocks are prone to collapse and roof fall. In order to ensure the construction safety in these places, the traditional double side wall and single side wall pilot pit method is generally adopted.

[0003] The divis...

Claims

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