Optimization Design Of The Support Of Foundation Pit For The Hunan Xinshayuan Project

With the rapid development of the social economy after the reform and opening up, exploiting the space overground and underground as well as strengthening the exploitation and comprehensive utilization of the land have become the theme of urban construction. With the renovation of the old city and the improvement of the rail transit, the underground design and construction technology of deep foundation pit project, underground tunnel of the rail transit as well as urban underground pipe network construction have become the hotspots and difficulties nowadays. The foundation pit engineering that this paper mainly studies needs to take the complex environmental requirements around the project site into account. The design of foundation pit under these circumstances becomes increasingly difficult. Deep foundation pit supporting engineering is a relatively complicated and comprehensive geotechnical engineering problem that relies on experience. It includes the surveying and mapping, structural engineering, engineering monitoring and environmental protection. The existing support construction technology and design theory has been unable to meet the requirements of the development of the supporting design for the deep foundation pit. In general, the success rate of the foundation pit engineering is still low. How to create a economical, safe and reliable design scheme for the deep foundation pit has become a very hot topic.This paper introduces the characteristics and development status of deep foundation pit engineering, the design theory of the foundation pit and the problems in the implementation of the support of foundation pit. Taking the foundation pit engineering of Xinshayuan project as the research object, we optimized the original supporting scheme according to the engineering geological condition at the site as well as the characteristics of the foundation pit and the surrounding environment. The supporting scheme of original row piles of foundation pit and high-pressure spiral jetting diaphragm is changed into low rigid pile and strong anchor on the west side of the foundation pit, pre-stressed anchor and soil-nailing wall on the east side of the foundation pit, soil nailing wall supporting on the south and north side of the foundation pit in terms of the supporting structure. Based on the supplementary investigation and test data, we made design calculation of the supporting structure parameters separately, including soil pressure, internal force and deformation of the supporting structure, stability calculation for supporting structure, treatment design in special circumstances, control design for underground water. The optimized design of the supporting scheme saves the cost of 3,260,600 yuan. From the perspective of construction and monitoring, the results were good. It achieved the desired goal of both economical and safe supporting scheme. The design is safe and reasonable. The research results provide a reference for the design of deep foundation pit with the similar geological environment of the city.