Theoretical Analysis And Computer Simulation Of The Construction Of Concrete Arch Dam Temperature Field, Temperature Cracks

Mass concrete structures play an important part in modern projects, especially in hydropower construction. As there are few or even no reinforced steels configured in the mass concrete structures, the great tensile stress will always appear due to the change of temperature in the structures, which may result in the initiation and development of cracks. Therefore, it is of significant to analyze the temperature field, temperature stress and crack initiation of the mass concrete structures in the constructional process.First of all, in this thesis, recent research situations about temperature control and temperature induced crakes in domestic and at abroad are summed up. Then, by using coupled analysis method, the temperature field, temperature stress and crack initiation of the arch dam are studied in details with the finite element code ABAQUS. The results and main works are listed as follow:1,Introduced the theory and calculation method about the temperature field, temperature stress and smearing cracking model;2,Established geometric model with ABAQUS software. In order to achieve the construction process that the concrete layers add one by one with time increased, the whole model is divided into several parts based on the different concrete pouring layers, and the life-dead element technology is used to control whethe the layer is on work or not.3,With the CHECK and ACTIVATION order in ABAQUS, the problem that the convection boundary conditions change with load steps is solved. During the construction process, the convection boundary condition on the top surface of the layer will disappear once the next concrete layer is poured, while there are no changes on its front and back.4,By using the redevelop technology of ABAQUS software and compiling the HETVAL and UMAT user defined programs, the process that hydration heat and Young's module change with the concrete pouring age is well simulated.5,Based on the arch dam model built above, the temperature field of the model is studied. The results show that, the temperature in the inner region of the arch dam is higher than the outer region, and as the time goes forward, the higher temperature diffuses from the inner region to the outer region to reach a stable situation.6,According to the linear elasticity and smeared cracking model constitutive relation models, the temperature stress and cracks distribution are analyzed respectively. The results indicate that, with the linear elasticity constitutive relation model, a tensile stress region appears near the shoulder of the arch dam area, whose values have exceeded the ultimate strength in tensile. While with the smeared cracking model constitutive relation model, the cracks, which lead to the redistribution of the temperature stress, will appear and develop at the same tensile stress region as linear elasticity constitutive relation model when the stress exceeds the ultimate strength in tensile...