Study On Key Techniques For Numerical Simulative Analysis Of Thermal Stress In Concrete Dams

The influencing factors about temperature control in the hydraulic concrete are so numerous, and the mechanisms are so complicated, that the accurate influences of many factors which influenced the course of the crack's arisen and its development still can't be simulated currently. The simulative model of temperature field and stress field in concrete , Heat and moisture coupling,Parallel simulative calculation of concrete with water pipe cooling, Parallel feedback analysis of thermal characteristic parameters, and stress intensity factor of induced joint, which are the sixty-four-dollar questions, are studied in this dissertation. The main contents of this dissertation are as follows:(1)Based on the past and current research work, the calculation theory of the transient temperature field and creep stress field of mass concrete which self temperature influence is considered is deduced. The couple effect between the temperature field and humidity field of concrete, is considered on the basis of conservation law of water and energy, and the coupled formulation which coefficient is not constant of the heat and moisture in concrete is deduced. The calculation theory and model which is theoretically strict for solution to thermal problem in concrete with water-cooling pipes are recommended. And the shortages of two simplifications are pointed out.(2)A new networked PC cluster parallel computing environment is set up, and the detailed method of configuration and use is presented. The parallelism of the FEM dealing with structure problems is analyzed, and the parallel computing strategy of FEM in distributed environment is introduced.(3)According to the higher and higher request of the simulation to scale, accuracy and time in the course of the large hydraulic engineering construction, The parallel simulative calculation to temperature field and creep stress field of mass concrete with water pipe-cooling is realized in distributed environment, and the technique is applied to an actual arch dam engineering which needs whole 3-D simulate.(4)On the basis of genetic algorithm which used for feedback analysis of thermal characteristic parameters, the improved genetic algorithm is advanced. The contrasts of the function test results show that the various improvements measures can resolve the low search ability of the algorithm in part area, and premature convergence. Considered the distributed environment, a coarse grained parallel genetic algorithm is put forward, the function test results show that the parallel efficiency and parallel speed-up ratio of the algorithm is high, and it is suitable for feedback of large-scale simulative calculation.(5)Three solution methods for SIF are introduced, the influencing factors in FEM are analyzed. Fractal theory is used to picture fracture phenomenon, and the relationship between the SIF of induced joint in concrete and fractal is analyzed too. A fractal model of SIF in I type fractal crack-tip is established on the basis of the fractal equations for concrete stress field and displacement field on the induced joint crack-tip in the state of plane. Then the fractal dimension seeking method for SIF is introduced, and the parallel method is suggested in 2-D problem. Actually seeking the fractal dimension for SIF of induced joint by normal way is very difficult, so a feedback seeking method is suggested.