Study On The Proposal Of The Third Stage RCC Arch Cofferdam For Three Gorges Project

Based on the design proposal of the third stage RCC arch cofferdam for the Three Gorges Project, proposed by Prof Zhang Zhongqing, this paper comprehensively studied it, using three non-linear FEM methods. In the procession, static analysis, stability against sliding analysis, modal analysis, response spectrum analysis, transient dynamic analysis, temperature field and thermal stress analysis are done, and in order to make the proposal perfectly, the optimization analysis is done too. Under the research work of my tutor, the following contents are studied.1. The stress field and displacement field under basic load combination are analyzed, and Point safety against sliding and stabilization safety factor against sliding are also analyzed, so that the structural condition under static load is completely studied.2. The failure mechanism of structure is analyzed, in this way the safety factor under water press overload is acquired, so that the safety stock and the failure processing can be clearly known.3. In order to know the structural condition under dynamic load clearly, modal analysis, response spectrum analysis and transient dynamic analysis to the structure are analyzed. In the response spectrum analysis, not only the earthquake load is considered, but also other loads including gravity, water pressure and temperature drop are all considered, for acquiring the practical action of load combination.4. Considering all kinds of changes of material and environment during the whole construction, the temperature field and thermal stress are analyzed.5. The mathematic model for optimization analysis is determined by founding parametric model, selecting the volume of arch cofferdam as object function, and selecting geometric constraint conditions, stress conditions and stabilization against sliding constraint conditions. The shape optimization of the structure is then analyzed to acquire perfect proposal.6. Based on the analysis of results, the merits and demerits of the arch cofferdam are evaluated from the point of safety and economical efficiency.