Excavation Supporting Schemes And Control Method Of Groundwater In Yancheng

Excavation engineering is a comprehensive system, the quality of which will put a direct impact on the progress, quality and cost of projects. Hence, the design of excavation supporting is a key part in excavation engineering. With the shortage of urban land resources, the adequate utilization of underground space becomes especially important. Therefore, much higher and strict requirements were proposed for the excavation and support of excavation engineering. Excavation engineering has characteristics as distinctive regional feature, high cost and the occurrence of collapse leads to serious consequences, therefore, the design of which must ensure the safty of the construction of this excavation engineering. The excavation supporting scheme must be scientific, reasonable, safe, reliable, convenient, feasible and the cost is low.There are many influence factors in excavation engineering. It will be very meaningful if we can establish an evaluation model according to factors in geological and hydrogeological conditions. The model is able to pick up the most safe, reliable, economic and reasonable scheme from comparing several different kinds of design schemes. This paper presents a design for the third phase of pioneer international square's excavation engineering in Yancheng city. The design is based on the geological situation in Yancheng city and the common foundation supporting scheme used beforehand. A theoretical analysis and a practical engineering analysis were used to analyze and illustrate the design comprehensively. An optimizied model was established, the weight of each parameter was determined, and an excavation supporting scheme as well as a groundwater control measurement were determined through calculates. The main content of this paper includes:(1) A review of domestic and foreign literatures, which includes a summary of the characteristics of excavation engineering, a summary of the existing excavation supporting scheme and its groundwater control technologies, a collection of existing excavation supporting structures and groundwater control measures in Yancheng city. This review is the theoretical foundation of this paper.(2) The fuzzy comprehensive evaluation method and the analytic hierarchy process were described. The influencing factors of these two methods were analysed and compared with the weight of each evaluation index determined. And an evaluation model for excavation engineering support Was established based on the fuzzy comprehensive evaluation method and the analytic hierarchy process (ahp)(3) Use the data collected from the third phase of pioneer international square's excavation engineering project in Yancheng city, and the established evaluation model of excavation supporting, to analyse and assess three kinds of excavation supporting schemes (supporting pile+anchor+anti-water curtain, soil nailing wall+supporting pile+water stop curtain solutions, underground continuous wall). The results show that the optimal scheme for this excavation supporting project is "pile+anchor+anti-water curtain". The application of this optimal scheme verified that the scheme optimized by the fuzzy comprehensive evaluation method is safe and reliable, economic and reasonable, and is able to provide guidance to similar projects.(4) Based on the optimized design scheme, a design for the third phase of excavation supporting scheme(supporting pile+anchor+anti-water curtain) of pioneer international square in Yancheng city was carried out, and the supporting structure and supporting system were calculated and analysed, to validate the safety and reliability of the design and the construction.(5) A dewatering design for the project was carried out.The stability control of groundwater in excavation engineering was analysed considering thesudden surge, the seepage stability and the dewatering of the foundation pit in this project.