Application of immune genetic algorithm to back analysis for parameters in model of rockfill dam coarse grain material

The method of combining the theory of finite element calculation of parameters in model of rockfill dam coarse grain material with the immune genetic algorithm(IGA) is confirmed;and a relevant software is developed.Using the large scale loading test data of Gongboxia dam,constitutive model parameters of rockfill are gained.It is concluded that because the mica schist is mixed with feeble weathered granite,the grain is broken up severely;the back-analysis parameters of explosion rockfill(3BⅠ)are lower than the results of laboratory triaxial test,and the Duncan E-B parameters obtained by back-analysis of her sandy gravel(3BⅡ)are higher than the triaxial test results of laboratory triaxial test which can not reflect the mechanical behaviors of the dam material objectively;the research should be strengthened in 300 m high rockfill dam construction.The fitting modes of the space displacement field of prototype observation are also explored and it turns out that the results of IGA analysis considering only vertical deformation meet the need of dam's technical accuracy.