Research On Static And Dynamic Characteristics And Bearing Capacity Of Qinglong "U" Shaped Arch Dam

With the continuous development of roller compacted concrete dam construction technology,the construction of RCC arch dam is becoming more and more mature.According to the topographic and geological conditions of the dam site,in order to be more suitable to play the role of arch,the double curvature arch dam is often chosen to be constructed in the"V" shaped river valley.The "U" shaped RCC dam which is high and thin is rare at home and abroad.The terrain conditions of Qinglong arch dam in Hubei province are particularly special,with the angle of slope in 628m-737m elevation up to 60 DEG-87 DEG;the mountain is steep,narrow and deep "U" shape,the thickness ratio of the valley is 0.18.Therefore,the figure of Qinglong arch dam is designed as a typical"U" shape thin arch dam.At present,the researches on static and dynamic characteristics and failure mechanism of the conventional "V" shaped arch were conducted by domestic and foreign scholars,but the relevant study on "U" shaped RCC arch dam is a minority?Based on these,the static finite element method(FEM)was used to analyze the static characteristics of Qinglong arch dam.The stress distribution of Qinglong arch dam is significantly different from the distribution of general "V" shaped dam.A large tensile stress area is shown in the downstream arch crown which is 1/4 dam height from the bottom of dam,and this proposes the discussion of the safety of the dam.To study the final failure mechanism of Qinglong "U" shaped thin arch dam and its safety factor,basing on the Drucker-Prager criterion,the ultimate bearing process of Qinglong arch dam was calculated and analyzed by using strength accumulation coefficient method and over loading coefficient method.By methods of recording the sudden change of the dam displacement and observing the connected plastic zone and the convergence in the evolutionary process,the failure mechanisms of Qinglong arch dam was discussed and the safety degree was evaluated.Analysis pointed out that the stress of Qinglong arch dam in the ultimate bearing process adjusts itself with the tension stress decreases or disappears,and the safety of dam meet the requirements.Finally,based on the finite element method of seismic dynamic analysis,the modal analysis of Qinglong arch dam was done to get the natural frequency and vibration mode,and dynamic response analysis of Qinglong arch dam was conducted by using dynamic response spectrum method and time history analysis method.The dynamic response characteristics of Qinglong arch dam which were different from that of the conventional "V"arch dam were summarized,and the theoretical foundation for the evaluation of the seismic safety of Qinglong RCC arch dam was established,and the corresponding seismic safety measures were put forward.The research results of this paper not only has practical guidance for the design and construction of the actual project,but also has some reference and significance to the similar projects.