Small-clear-distance U-shaped entrance and exit channel open-and-dark excavation construction method vertical conversion construction method

Abstract

The invention belongs to the field of urban rail transit design and construction methods, and relates to a small-clear-distance U-shaped entrance and exit channel open-and-dark excavation construction method vertical conversion construction method. According to the method, an open cut tunnel sleeve arch bearing structure formed by internally and externally overlapping a protective arch and a steel frame is arranged, conversion from open cut layered excavation to underground excavation blocked excavation can be completed in the vertical direction, a prestressed anchor cable arranged on the lower portion of a foundation pit is adjusted into a system anchor rod, the purpose of safe, efficient and rapid construction of an open cut tunnel and an underground excavation tunnel in advance in an external anchor supporting mode can be achieved, construction of the subsequent small-clear-distance underground excavation tunnel is not affected by invasion of the prestressed anchor cable, the problems that a construction site is insufficient and the work efficiency is limited can be effectively solved through the backfill ground surface area of the top of the open cut tunnel overlapped sleeve arch, and the method has the advantages of relieving the early-stage work difficulty, improving the mechanical operation level, reducing the civil construction risk, reducing the peripheral letter visit pressure and shortening the engineering construction period, and is very remarkable in social, engineering and economic benefits.

Description

Technical field [0001] The present invention belongs to the field of urban orbit transportation design and construction method, which can be expanded, applied to the field of municipal engineering construction, especially related to the surrounding environment, limited ground space, when the construction is nervous, formation "guard arch + steel frame "Inside and outside, the pilot, the pilot, the small net distance" U "-shaped entrance and exit channel rapid construction method and corresponding implementation method, has the improvement of the preliminary work, improve the mechanical operation level, and reduce the risks of civil construction , Reduce peripheral petition pressure, shorten the advantages of engineering construction cycle, social, engineering, and economic benefits are very significant. Background technique [0002] Urban orbit transportation project is positioned in service urban, linkage, forming the ring, longitudinal radiation area of ​​urban subway and perip...

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Problems solved by technology

[0004] The construction efficiency of the pile support enclosure is low, the internal support cuts the construction space seriously, and the support elevation easily interferes with the construction route of the underground excavation channel, conflicts and is difficult to overcome. It is impossible to realize large-scale mechanical construction operations, and only small-scale machinery can be used to gain space in time , the construction period is difficult to control; in addition, the excavation of the backward underground excavation channel will form an unloading area for the soil behind the pile, which is not conducive to the stability control of the pile-support system. The greater the impact, the higher the construction risk;

[0005] The form of pile and cable enclosure is not conducive to the construction organization and arrangement. Not only the excavation support and structural modeling construction are interlaced and interfered with each other, but also the construction of the subsequent underground excavation will cause damage and pollution to the existing finished structure and waterproof materials in the open excavation section. In particular, the pre-embedded steel edge waterstop at the interface between the new and old structures at the boundary between open and dark excavation is more difficult to protect the construction joints that are prone to seepage through;

[0006] The project volume undertaken by one-way construction and penetration of underground excavation is relatively large. Although the construction risk is controllable, it is extremely unfavorable for civil construction period and economic cost control when the open excavation section adopts the conventional form of enclosure structure; while the construction of two-way penetration The labor intensity of slope excavation is high, it is difficult to ensure the timely closure of the initial support, the face of the tunnel and the rock mass of the vault are prone to collapse, and the safety allowable length of the construction of the upside slope and the two-way penetration position are greatly dependent on the geological conditions, and the construction risk factor has increased sharply. Increased risk management costs with unacceptable risk consequences;

[0007] The three major engineering construction indicators of safety, construction period, and economy collide with each other, and it is difficult to compromise. The construction unit loses sight of one another and cannot have both. In severe cases, it will even restrict the key time nodes of the entire line, such as electrical communication, joint commissioning, and operation, which is extremely unfavorable. Stability of public opinion and output of social benefits

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