| With the advance of the urbanization process in the old urban areas, deep excavation projects are carried out in the complex environment. The supporting system needs to satisfy both safety of the underground structure during construction and the normal usage of the nearby buildings. Single supporting structure cannot satisfy both of the requirements, hence the composite supporting system which can solve this problem developed rapidly these years.In this paper, the problem of deep foundation pit supporting is solved by using the composite support structure of pile anchor and soil nailing in the complex environment of the electric tunnel, the hole and the old pile foundation in a deep foundation pit in Zhengzhou. This paper mainly do the following:The research status and common problems of pile anchor supporting and soil nailing wall retaining during construction are summarized and analyzed. The research status of Pile-anchor/Soil-nailing Composite supporting system are summarized and the advantages of the system are analyzed in this paper.According to analyzing the construction positions, soil parameters, construction conditions and nearby building safety control, the pit which interact with nearby existing electric tunnel, air-raid shelter and old pile foundation, using Pile-anchor/ Soil-nailing Composite supporting system to accomplish the project. The FEM and Code method are used to calculate the displacement of the pit during construction, the result show that the composite supporting system can satisfy the requirements of the complex environment.The vertical displacement and settlement of the pit measure points, deep horizontal displacement and displacement of nearby building is measured, the results show that by using the Pile-anchor/Soil-nailing Composite supporting system the soil displacements arre controlled rigorously and the building displacement is very limited. The result show that the Pile-anchor/Soil-nailing Composite supporting system can used in complex environment. |
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