Foundation pit soil nail retaining and protecting structure and method

Abstract

Provided is a foundation pit soil nail retaining and protecting structure and method. A foundation pit is excavated downwards for one to two meters, and inclined downwards drilling is conducted through facing a soil surface through adopting a drilling machine. A soil nail is placed into a drilled hole, and grouting is conducted on the hole; steel bar meshes are paved on the surface of the foundation pit wall, concrete is sprayed on the surface of the foundation pit wall till the steel bar meshes are covered with the concrete, a lower bearing structure under the nail is arranged between the lower portion of the soil nail head and the steel bar meshes, a concrete surface is sprayed on the lower bearing structure under the nail to form a soil blocking surface, retaining and protecting for a layer soil nail is completed, and the finished processes are repeatedly conducted till the bottom of the foundation pit is supported. Small prestress is exerted on the soil nail, and the soil nail is locked on the lower bearing structure under the nail through a nut; two box iron flanges are fully sprayed with concrete, and the concrete of the two box iron flanges and the concrete of the soil blocking surface are solidified and connected to be a whole. Due to the fact that the nail lower bearing structure is arranged, the soil nail is locked through the nut, the defects that the prestress can not be exerted on the soil nail, and piercing destruction caused by the nail head in the surface is prone to occurring are overcome, a pressure field can be formed in a certain range under the surface layer of the pit wall through exerting the small prestress on the soil nail, the deformation of soil body is reduced, and the safety and the stability of construction are improved.

Description

technical field [0001] The invention relates to a foundation pit soil nail support structure and method, which are used for reinforcement and support in various foundation pits, side slopes, tunnels and underground projects. Background technique [0002] In the reinforcement and support technology of foundation pits, slopes, tunnels and underground engineering, soil nailing technology is widely used. However, because the traditional soil nailing support technology is a passive support technology, that is, soil nails begin to bear force and play their supporting role only after the soil is deformed. There are two outstanding serious problems and fatal defects: (1) It is impossible to apply prestress to the soil nail rod body, so the vertical settlement and horizontal deformation of the foundation pit surface are very large, which may easily lead to cracking of the pipe network or buildings around the foundation pit; (2) The soil nail rod body is generally welded with transver...

AI Technical Summary

Problems solved by technology

The foundation pit soil nail support structure proposed by the present invention is based on two prominent serious problems and fatal defects in the traditional soil nail support structure: (1) It is impossible to apply prestress to the soil nail rod body, so the vertical settlement of the foundation pit surface and The horizontal deformation is very large, which will easily lead to cracking of the pipe network or buildings around the foundation pit; (2) The soil nail rod is generally welded to the transverse reinforcement or welded to the well-shaped steel bar. The connection is very weak, and it is easy to produce concrete "thorn "wear" failure, leading to failure of soil nail bearing capacity

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