Optimization Research For Anti-Seepage Drainage System Of Dam Foundation By The Improved Genetic Algorithm And The Finite Element Method

According to the Statistic data of practical engineerings,multitude engineerings have integrated anti-seepage and drainage to dispose of dam seepage, and accorded with the design fundamental"fore block up -and- aft dredge", so the anti-seepage and drainage certainly should be a combination to solve dam seepage.The design parameters of grouting and drainage curtain are numerous, in many times, which are confirmed by engineering geology, hydrology geology, experience formulas, or referring to the existed engineering cases. For middle or low dam in simple engineering and hydrology geology, the engineering requirements generally can be satisfied, but for high dam or complicated geology, other methods should be adopted to analyze and calculate, for important engineerings require field-tests to ensure these parameters, so it's difficult to reach the goal that not only safe and credible, but economic and rational.So it's very important to study the optimization of the anti-seepge and drainage of dam foundation. Anti-seepage structures can control the seepage discharge and reduce uplift pressure effectively, as well as have safety and good durability. From the view of optimization design, the safety should be satisfied with certain restriction condition, and the economy should make the cost (objective function) least.Based on the seepage analysis of the dam foundation, simple formula has been deducted in the text according to the experience formula of the existed grout curtain, by presenting an example of a concrete gravity dam on common rock foundation. Then can draw the simple and display expression about seepage discharge, uplift pressure in dam foundation and hydraulic gradient of the curtain. The parameters array can be gained by thinking the minimum cost of the grouting curtain as the objective function. But it's impossible to denote the cases accurately with simple formulas. In order to accord with actual model and get the seepage field in dam foundation, the text adopts finite element method rather than formulas. To Regard dam foundation and curtain grouting as heterogeneous anisotropic continuous media, taking the half depth of the curtain as plot length.Considering the simple genetic algorithm as a search algorithm for global optimization and a strongrobustness, facing its disadvantages that the time is long of search, premature convergence and weak search local optimization, the adopted optimum methods have been improved by combining the merits of mix choice, adaptive and complex method. Finally, the optimum combination of the parameters can be solved with the improved genetic algorithm, used seepage field by EFM as restriction condition, the cost of the grouting curtain as the objective function, and build a foundation for seeking optimum drainage system. So it can be put into the cases, and provides references for application.