Foundation Pit Supporting Design And Plan Optimization In Taiyuan Wanda Square

With more and more mature, foundation pit supporting technology has made great success in some ways. But because the environment around foundation pit is more and more complex, the depth of the excavation is more and more big, and the engineering geological conditions become more and more poor, the problems encountered in the design and construction process of the excavation is also more and more. The foundation pit engineering is still a technical problem, because of its big rick and high difficulty. Therefore further research on the design and construction of foundation pit engineering is needed. The foundation pit engineering accidents are common in our country, a lot of which was caused by improper supporting scheme selection. It’s very necessary to find a set of feasible theory to support foundation pit.This article is based on the excavation project in Wanda Plaza, Taiyuan. Firstly the advantages and disadvantages of the common forms of foundation pit supporting structure are discussed, as well as the scope application. Discuss the calculation of soil and water pressure, which should be considered in design, and analyze the deformation of the excavation. And then summarize the geotechnical engineering and hydrogeological conditions in the project site. Comprehensive evaluation was done of hydrogeological corrosive and sandy soil liquefaction. The required parameters of foundation pit supporting design are given. The design of the deep foundation pit supporting and precipitation was put out. This paper discussed the construction technology of the solider pile wall, deep mixing pile and high pressure jet grouting pile. Lastly, based on the basic principle of analytic hierarchy process and fuzzy comprehensive evaluation, the Wanda Plaza excavation project is optimized. The conclusion is as follows.(1)The form of foundation pit supporting should be reasonable selected according to the engineering characteristics in practical projects, which can be single supporting form, or combined form, in order to achieve better results.(2) Supporting structure deformation will lead to the destruction of the retaining structure; the building wall around the excavation will be crack or collapsed. The ground settlement around the foundation pit should be control focused in the design.(3) The ground mixed water level in Taiyuan Wanda Square excavation project site is between 0.70 ~ 3.50 m, which has close link with the Long tan Lake hydraulic groundwater. The influence of the groundwater must be considered in the design of foundation pit supporting.(4) The supporting method of this project adopts the solider pile wall + prestressed anchor supporting method; two sections are stetted according to the geological conditions of site and foundation pit digging deep. The slope protection pile diameter is 800 mm/900 mm; pile length is 16.7 m/20.1 m. The curtain for cutting off drains are three rows of deep cement mixing pile, between of which,one high pressure jet grouting pile is constructed in parts.(5)The analytic hierarchy process and fuzzy comprehensive evaluation method are combined used for three kinds of possible supporting, and score sorting in the form of data. Pile anchor support scheme is the highest rated conclusion, namely the pile anchor supporting is the optimal solution and agree with the original design scheme, theoretically support the scheme.