Optimization Research For Anti-Seepage Curtain Of Dam Foundation With The Thoery Of Coupled Seepage And Stress Fields

The research of seepage and stress fields coupling has become one of the frontier projects in geotechnical engineering. The design and optimization of the seepage-control for the dam foundation is not only the important guarantee of maintaining the dam and dam foundation stable, but also the effective measure to reduce the cost of the engineering. Based on studying the research of seepage and stress fields coupling both at home and abroad, and the design of seepage-control for dam foundation, the 3D-unsteady seepage and stress fields coupling of fracture rock masses with equivalent continuun medium model is studied. The optimization design model (which the goal function is the cost, the restriction includes the seepage quality over the curtain, the biggest hydraulic grads of the foundation and the whole seepage presure of the dam base) of seepage-control, which includes the theory of seepage and stress coupling, with the method of improved genetic algorithm is proposed.The main solutions presented in this text can be summarized as follows:(1) The coupling models of seepage and stress fields in fracture rock masses are studied, and the strongpoints and weakpoints of different models and its applied conditions are analyzed, that is, different geology of the projects choice differect model to analyze coupled seepage and stress fields.(2) Based on the theory of 2D and 3D-seepage and stress fields coupling, with the continuun medium model, the softwares of coupling are developed and combined with improved genetic algorithm to optimize the Anti-seepage curtain of high dam.(3) To the rock masses that distribute densed fracture, 2-D and 3-D unsteady seepage and stress fields are studied with equivalent continuun medium model. The calculation results of engineering examples indicates that the effects of coupling make the seepage quantity over the cross-section decrease and the hydraulic heads of dam foundation increase, that is, bigger water presure in rock fracture is produced. Besides, the effects of coupling make the hydraulic head of dam foundaion lag while the water level falls, and the bigger speed of falling, the more obvious of lag effection, and sharper hydraulic gradiend is produced.(4) The effects of coupled seepage and stress fields make the components of stress field increase. But while the water level falling with different speed rates, the stress fields make little change.(5) The mathematical model for the optimizaiton design of seepage-control system is established with the effects of coupled seepage and stress fields. For the shortcomings of the simple genetic algorithm, such as too long time to astringe, premature easily, the improved genetic algorithm is used to design the optimization program.(6) Unsteady seepage and stress fields coupling is studied and analyzed for a high dam which seepage-control system is optimized with the effects of coupled seepage and stress fields by improved genetic algorithm. The calculation results, that the optimization combinations of the curtain parameters of the dam, indicate that it is of good astingency to optimize the function of several variable with improved genetic algorithm.