Combined pile supporting structure for cylindrical foundation pit and construction method

Abstract

The invention provides a combined pile supporting structure for a cylindrical foundation pit and a construction method. The combined pile supporting structure comprises a supporting pile enclosure structure, an annular inner support and a hydraulic jack counterforce system located between the supporting pile enclosure structure and the annular inner support. The enclosure structure is an annular enclosure structure defined by H-shaped steel and U-shaped steel sheet piles in a staggered mode. The hydraulic jack counterforce system comprises a hydraulic control system and a plurality of hydraulic jacks arranged between the support pile enclosure structure and the annular inner support in a scattered mode. In the construction enclosure structure, the lateral rigidity of the cylindrical foundation pit is controlled and improved through the servo hydraulic jacks; meanwhile, the support pile soil pressure and the inner support axial force are monitored for early warning. The construction method and equipment have the advantages of being simple in construction process, small in construction machinery, small in occupied area, formed by prefabrication and assembly, high in adaptability and rapid in construction, having the double effects of supporting and water stopping, and having high application and popularization value.

Description

technical field [0001] The invention relates to the technical field of underground space development, in particular to a cylindrical foundation pit combined pile supporting structure and a construction method. Background technique [0002] With the introduction of the "14th Five-Year Plan", my country's urban construction has entered a new stage, especially the renovation of old cities and urban renewal. However, urban land resources are limited, especially in old urban areas. Due to insufficient development planning, numerous underground pipelines, and complex building property rights, the utilization efficiency of underground and above-ground space is greatly restricted. As a result, problems such as "difficult parking" in old urban areas and residential areas have greatly affected residents' happiness. As the times require, there are underground garages built with the purpose of saving land resources and making full use of underground space, and the cylindrical undergrou...

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Problems solved by technology

[0003] As we all know, in the construction of cylindrical underground garages, the most difficult, most regional and most important is the cylindrical foundation pit support project. The traditional foundation pit support is more commonly used to use SMW construction method piles and steel sheet piles, SMW Construction method piles and steel sheet piles are difficult to control the construction quality and have poor stratum adaptability, so that the water-stop effect is poor and the stability of the foundation pit is difficult to guarantee in areas with abundant groundwater; the traditional foundation pit supports are mostly concrete supports or steel supports. Poor adaptability in cylindrical foundation pit

Moreover, the existing cylindrical foundation pits, such as subway ventilation shafts, pipe jacking shafts, mine vertical roadway shafts, etc., due to the existence of circular arch effects, the earth pressure of the enclosure structure is different from that of common polygonal or special-shaped foundation pits. Compared with traditional polygonal or irregular foundation pits, the unique ring effect of cylindrical foundation pits reduces the bending moment of the support structure due to earth pressure, which is referred to as "ring" in relevant specifications. There are often errors in the construction of foundation pit support piles, which makes it difficult to ensure the "true roundness" of cylindrical foundation pits, thereby greatly reducing the "circumference stiffness" and increasing support costs

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