Construction Method of Composite Foundation Pit Support with Horizontal Jet Grouting Soil Anchor and Cast-in-situ Pile

Abstract

The invention belongs to the technical field of foundation pit supporting for high-rise buildings, in particular to a foundation pit support construction method combining horizontal rotary jet-grouting soil bolting and bore concrete piles, which includes steps: firstly, constructing water-stop mixed piles and bored concrete piles according to a preset foundation pit; and secondly, performing soil excavation and soil bolting layer by layer and section by section. The foundation pit support construction method has the advantages that the foundation pit support constructed by the method is high in deformation control performance and stability and especially applicable to projections with high requirements on foundation pit deformation, and the method is applicable to mega-area foundation pit supporting in soft soil areas with failure of using internal support structures, limited slope reduction conditions and excavation depth limited within 15m, and meets the requirement that development and utilization of urban underground space continue to develop.

Description

technical field [0001] The invention belongs to the technical field of foundation pit support of high-rise buildings, in particular to a construction method for composite foundation pit support of horizontal jet grouting soil anchors and cast-in-place piles. Background technique [0002] In the southeastern coastal areas of China, with the rapid development of urban construction, high-rise buildings and super high-rise buildings are constantly emerging. Due to the needs of structure and function, one to three-story basements are generally set up. Most of the coastal areas are of soft soil, and their geological structures are generally It is: cultivated soil or miscellaneous filling soil about 1 meter thick on the surface, clay soil 1-2 meters thick below the surface soil, and silt soil or silty soil tens of meters thick below the clay soil. Due to coastal areas, especially offshore areas The soil quality is extremely poor. Generally, foundation pits with a depth of more than...

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Problems solved by technology

[0002] In the southeastern coastal areas of China, with the rapid development of urban construction, high-rise buildings and super high-rise buildings are constantly emerging. Due to the needs of structure and function, generally one to three floors of basements are set up. Most of the coastal areas are of soft soil, and their geological structure is general. It is: cultivated soil or miscellaneous filling soil about 1 meter thick on the surface, clay soil 1-2 meters thick below the surface soil, and silt soil or silty soil tens of meters thick below the clay soil. Due to coastal areas, especially offshore areas The soil quality is extremely poor. Generally, foundation pits with a depth of more than 6 meters must adopt a support structure of bored piles and internal supports. This foundation pit support structure has better overall safety, but it has the following disadvantages: a large amount of concrete support materials , it is necessary to add high-cost support structures such as column piles and lattice columns; the speed of excavation is affected, and the earthwork often needs to be turned over many times, which affects the construction period; the process of removing and replacing braces is added, and the removal and replacement of braces is unreasonable , in addition to increasing the deformation of the side wall of the foundation pit, it will also have an impact on the main structure; for super large-area foundation pits, it is difficult to implement internal support

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