Research On Key Problems And Dynamic Simulation For Top-Down Construction Technique

As domestic cities and towns progress faster and faster,building construction meets problems of restrict control on site area and circumstance protection.In result, Top-Down Construction Method (TDCM) gets more and more application which promotes its progress. Whether on theory or practice, there are quite lot problems and questions in TDCM need to be solved, which relates to the selection of the construction scheme, improvement and reform in key techniques and skills of construction, selection of the deep foundation pit dewatering, control on the settlement of columns or piles, the calculation method the safety factor for the whole process of TDCM and so on, this dissertation was carried out research and investigation on problems above.The key techniques of TDCM on design and construction were studied in this dissertation. On diaphragm walls that were used as a part of main structures, some design and construction of measures, and reliable joint structures between diaphragm wall and basement beam or plate were extensive analyzed.On pillars, the supporting load ways, joint structures between pillar feet and pile cap were researched, the working mechanism and construction control of settlement on pillars were discussed. In addition, some special difficulties of TDCM were also solved.It was introduced, and successfully applied that Simulated the structures of the TDCM and soil base on the Finite Difference Method with computer. Then deep foundation pit dewatering was simulated with the uncoupled flow-mechanical approach. Finally the flow chart for dynamic simulation of the whole process of TDCM was presented.Using the dynamic simulation techniques, the dissertation studied the structure-foundation-soil interaction under TDCM construction process. Through analysis the different TDCM construction methods, study the principle of differential settlement between diaphragm walls and pile. The dissertation compared the effect of different construction methods and dewatering approach. It can be known the displacement of diaphragm walls and pillar piles, summarized the impact of TDCM construction and dewatering approach on the surrounding circumstances.Then the Finite Difference Method that base on the strength reduction theory to analysis the safety factor of the whole process of TDCM was presented. The calculation method, that analysised the safety factor, was verified efficaciously and valuably for the foundation pit of TDCM.