Research On Deep Foundation Pit Supporting Scheme And Construction Of Jiujiang Linghu Spring

With the rapid development of society and economy, urban population becomes more and more, and the lands are more important. People’s demand for space is more urgent than ever before, so more and more deep foundation pit projects are appearing. The characteristics and the accident causes of deep foundation pit project were analyzed. The construction method, the advantages and disadvantages, and the application scope of several common supporting structures were discussed. Based on the geological and hydrological conditions, and land use planning of Jiujiang, three cases of deep foundation pit projects in Jiujiang city were analyzed comparatively from four aspects:the geological conditions, groundwater conditions,surrounding environment, the determination of supporting scheme and so on. Some suggestions were given for the determination of the foundation pit supporting scheme in Jiujiang city according to the comparative analysis. The research project of this paper is Jiujiang linghu spring which located at Jiujiang Balihu new zone in Jiangxi province. A planning road passes through the middle of the project block, and divided it into south block and north block. The total construction area is 193,000 square meters. The excavation depth is 5.5 to 7.05 meters. According to the general situation of Jiujiang linghu spring, this paper studied on the determination of the deep foundation pit supporting scheme, the designation, the construction scheme determination, the pit deformation survey and so on of the project combing with the research results of this paper. The main results obtained are as follows:1. Based on the geological and hydrological conditions, and Jiujiang land use overall planning(2006-2020), three cases of deep foundation pit projects in Jiujiang city were analyzed comparatively from four aspects:the geological conditions, groundwater conditions, surrounding environment and the determination of supporting scheme. The results were found as follows:1) the soil conditions of most projects in the planning zone of Jiujiang city.2) the underground water and the surface water system are rich, the annual rainfall is plentiful and the underground water supply is sufficient in Jiujiang city. So in the process of the foundation pit project construction should pay attention to construction precipitation.3) the construction lands in the concentration region of foundation pit project in the future are mainly wastelands or cultivated lands, and the surrounding environments of foundation pit projects are relatively simple in Jiujiang city.2. The geological and hydrological condition, excavation depth, surrounding environment, the cost and many other factors of the proposed site should be considered comprehensively in the determination of most deep foundation pit supporting scheme in Jiujiang city. Different supporting structures could be used in different areas of the same foundation pit project according to the specific circumstance. Grading process could be used preferentially if the site permitted, otherwise soil nailing wall could be used. Composite soil nailing wall could be used when the excavation depth was big or the underground water was rich.3. The geological and hydrological condition of Jiujiang linghu spring deep foundation pit supporting project was typical in Jiujiang city. According to the suggestion above, multi-row deep mixing cement soil pile supporting method was used in the south block deep foundation pit of Jiujiang linghu spring, and soil nailing wall combined with steel pipe pile supporting method was used in other part. The stability and strength of the supporting scheme were verified through calculation.4. The construction method and process of Jiujiang linghu spring deep foundation pit supporting project were discussed in detail. Reasonable construction organization design was designed. The drainage measures combing with open drain and collection well were used in the construction to ensure the requirements of the construction surface. The deformation displacement of foundation pit soil was studied and evaluated during the construction with comprehensive consideration of the safety of the surrounding environment. The deformation survey of the pit verified that the supporting scheme is feasible. The supporting scheme of Jiujiang linghu spring deep foundation pit worked well in the construction.5. The results in this paper can provide reference for the selection of the supporting scheme, the design and construction of the supporting structure of deep foundation pit projects in Jiujiang city.