Shallow underground excavation unsymmetrial loading tunnel roof caving in-hole forepoling method

Abstract

The invention discloses a shallow underground excavation unsymmetrial loading tunnel roof caving in-hole forepoling method. The method comprises the following steps that advanced geological predictionis carried out; in-hole back pressure backfill is carried out; guide frame erecting is carried out; advanced pipe shed supporting is carried out, and steel cages are sleeved with seamless steel pipesof all pipe sheds for grouting subsequently; earthwork is excavated from top to bottom; initial supports are applied under the pipe sheds, joist steel adopted by initial supporting after initial supporting is completed is used as supports to drive advanced small pipes, grouting is carried out after the advanced small pipes are driven, and supporting is completed. By means of the shallow underground excavation unsymmetrial loading tunnel roof caving in-hole forepoling method, a manner of supporting the advanced pipe sheds and then driving the advanced small pipes is used for supporting the tunnel roof caving position, the pipe shed supporting angle is large, strong supporting is formed at the tunnel collapse position at the maximum extent, later initial supporting and advanced small pipe arranging are further facilitated, meanwhile, a pipe shed working chamber does not need to be excavated during initial supporting.

Description

technical field [0001] The invention relates to the field of tunnel construction, in particular to a method for advance support in a cave at a roof fall of a shallow buried excavation bias tunnel. Background technique [0002] For road construction in mountainous areas, tunnels are indispensable structural engineering, which can effectively reduce the length of roads and optimize linearity. During tunnel construction, especially in tunnels with sandy clay soil, roof fall and collapse accidents often occur, and the ground surface is often used to reinforce the collapsed body, and advanced support measures such as pipe sheds or advanced small conduits are installed in the tunnel. For example, on October 19, 2018, the State Intellectual Property Office of the People’s Republic of China disclosed a method for the treatment of roof fall in sandy clay geological tunnels, including: advanced geological prediction, roof surface treatment, reverse pressure backfilling in the cave, ad...

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Problems solved by technology

[0003] The above construction method has requirements for the external insertion angle of the pipe shed (5°~10°) and the pipe shed working room. The external insertion angle of the pipe shed is too small. If the pipe shed is constructed at this angle during actual construction, the front support will be damaged. Therefore, it is impossible to build a large pipe shed according to the original design requirements (after the roof falls, the upper soil layer is soft, and there is no condition to excavate the pipe shed studio. If it is excavated rashly without treatment, it will lead to a second roof fall)

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