Support system of rear support removing type section steel-concrete double-enclosing-purlin foundation pit and construction method

Abstract

The invention discloses a support system of a rear support removing type section steel-concrete double-enclosing-purlin foundation pit and a construction method. The support system comprises an enclosing wall located in the foundation pit, a plurality of horizontal supports located on the inner side of the enclosing wall, an enclosing purlin fixed on the enclosing wall and an enclosing purlin fixed on the horizontal supports. A plurality of bars of horizontally arranged section steel is arranged between the double enclosing purlins, and vertical steel bars in a structure wall penetrates through slits between the section steel and the double enclosing purlins from top to bottom. The structure is reserved all the time at a back building stage until a horizontally stressed system of an underground main body structure is formed and can support the enclosing wall, then part of section steel extending out of the inner side of the structure wall is removed, and a whole reinforced concrete support is removed. The fact that the stressed requirements of a horizontal support system at an excavation stage of the foundation pit are met is guaranteed, lateral deformation is resisted, construction progress is accelerated, cost is reduced, construction quality is improved, a novel designing idea is provided for a deep foundation pit support system with an oversized area, and construction difficulty of a rear support removing system at a structural back-building stage is reduced.

Description

technical field [0001] The invention belongs to the technical field of building construction, relates to an underground engineering foundation pit support system and a construction method of the system, and is suitable for the situation that the foundation pit support system needs to be retained in the restoration stage of an underground main structure. Background technique [0002] With the development of urban construction, urban buildings and infrastructure are becoming more and more dense, which reduces the construction space of underground projects and complicates the construction environment; on the other hand, as the development of underground space develops in a large-scale and complex direction, The excavation area and depth of foundation pits in underground engineering are getting larger and larger, and the flexibility of underground structure layout and building requirements are getting higher and higher. In underground engineering, due to the limitation of constr...

AI Technical Summary

Problems solved by technology

There are some technical problems that are difficult to solve in this post-brace method: the purlin and the structural wall are concrete poured in different periods, and the purlin becomes a part of the structural wall later, whether the joint force of the two is reliable and how to waterproof the interface The problem is that the vertical steel bars of the wall cannot penetrate the purlins of the supporting system during the structural restoration stage, and all need to be disconnected and overlapped with the reserved steel bars in the purlins, which makes the integrity of the structural steel skeleton poor and affects the structural concrete pouring. The structural construction cannot work continuously, which directly affects the construction progress and construction quality.

There are also certain limitations in the method of replacing the diagonal brace: when the distance between the upper fulcrum of the diagonal brace and the bottom plate is large, the length of the diagonal brace will increase accordingly, which will affect the performance of the diagonal brace as a compression bar. Stability; when the diagonal brace passes through the constructed structural floor of the lower floor, a large hole in the structural floor is required. After the diagonal brace is removed later, it will be poured and filled. There is a problem of whether the joint force of the concrete structure poured in different periods is reliable; A large diagonal brace will greatly increase the amount of engineering materials such as steel and concrete. Considering the construction period, not only will the construction cost be increased, but the construction progress will also be greatly affected.

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