Research On Ground Motion Characteristic At The Site Of Large-scale Valley

This paper briefly reviewed the current research on the characteristics of site, summed up and briefly commented the ways of analysis on the ground motion characteristics of local site. Author researched on the characteristics of large valley terrain of the ground motions through second development of the commercial software FLAC. Summarized as follows:First, according to the theories of viscous-spring artificial boundary and transmitting artificial boundary, the ways of forces about the viscous-spring artificial boundary under the conditions of scattering and radiation problems had been considered respectively. Viscous-spring artificial boundary and transmitting artificial boundary could be in the FLAC with FISH compile program in FLAC finite differences program. The validity of near-field fluctuation problems simulation by Viscous-spring artificial boundary and transmitting artificial boundary had been testified with an example.Second, according to a triaxial shear test data, an elastic-plastic constitutive model had been obtained in the paper by repeated adjustment of relationship between the plastic strain and model parameters to fit experimental stress-strain curve. Meanwhile, an elastic-plastic constitutive model had been proposed for dynamic calculation of a rock material which by the use of FLAC static model of hardening softening constitutive model. Based on plastic strain, the model could adjust the constitutive relation in the process of the calculation and directly reflected the elastic-plastic properties of soil.Third, according to the use of elastic-plastic constitutive model which determined as above and software of FLAC, a specific research of site properties in the topographical sites of valley with two different depth-to-width ratio had been discussed here and analyzed the characteristics of ground motions of the free surface, valley shoulder, foots of valley slopes, valley bottom and other special locations in valley.