The Research Of Inversion Algorithms On Dynamic Parameters Of Earth-rock Dam

Seismic design of earth-rock dam in general need to analyze earthquake dynamic response to determine the dynamic response and deformation of the dam, then judge the dam seismic safety. Dynamic calculation of the earth-rock dam is based on a given soil parameters for the premise. The traditional soil parameters are determined by field wave velocity test or cyclic simple shear and dynamic triaxial test in laboratory and etc. Because of the complexity of the dam filling site, the result of the field wave velocity test is more uncertainty. Field test can only provide maximum dynamic shear modulus; do not provide modular attenuation ratio curve, the damping ratio and etc. Laboratory test of the rock in dam filling is in the fixed density. Indoor test control density and dam filling density often is not the same, and the real density of the dam filling is not equably influenced by construction technology, construction method and construction quality. Indoor results by equipment precision influence are bigger, so experiment measured parameters value is not fully reflect the real. For design small and medium-sized earth-rock dam project, there is not indoor dynamic triaxial test. The dynamic parameters are determined by the engineering experience.On the other hand, the existing many earth dam suffered an earthquake or aftershocks, some dam were measured significant quantities of dam body reaction information, but at present it do not make full use of the information.This paper aims to find a method what is using seismic response of the dam information to inverse earth-rock dam dynamic parameters of the materials. It is examined the accuracy of the method that determine the earth-rock dam dynamic parameters, in order to improve the reliability of earth-rock dam seismic response analysis and provide the foundation for seismic design level.In this paper, inversion method of the dynamic parameters of earth-rock dams is established using genetic algorithm based on the floating-point coding and theory of finite element. The real soil parameters are inversed according to acceleration responses of limited measuring points in the process of earthquake. Using the inversion method respectively perform the modulus coefficient K, modulus index n, and maximum damping ratio λmax of the core dam and faced dam body material.Because the local search ability of genetic algorithm is poorer, introducing the hill climbing that has strong local search ability into the genetic algorithm to improve the algorithm in order to improve the efficiency and reduce optimization calculation. The inversion effect of improved algorithm is obviously improved.