Numerical Experiments Study On Scalling Effect Of Deformation Properties Of Coarse-grained Materials

Earth-rockfill dam is an important hydraulic structures, the safety problem has always been the focus. The dam’s deformation and stability are related to coarse-grained materials directly, which is the main dam’s materials.With the increase of high earth-rockfill dam construction and development of damming technology, the dam with the largest particle size of coarse-grained materials is close to 1 m. Currently, there is no directly measurement of testing original grading mechanical properties. Using the existing test equipment, the original grade ingredients must be scaled. Some research results and monitoring data show that mechanical characteristics of coarse aggregate has difference before and after scalling.The mechanics characteristics of coarse-grained materials on scalling can not reflect the mechanical properties of gradation coarse grained material. There are much more study on size effect. The method hasn’t been put forward, which on the base of the after scalling results of coarse aggregate determine the original gradation for mechanical parameters of dams coarse aggregate reasonably.This paper adopts the method of discrete element numerical test. Analysis the inner link on strength and deformation characteristics of coarse-grained materials about before and after scalling. Exploring the method of determine the original coarse material mechanics parameters according to after scalling of coarse aggregate grading laboratory test results. The work is conducted as follows.Combined with a project of dam’s wide grading coarse material test, reference for the large conventional triaxial compression test specimen size, biaxial shear numerical test model is established. The calculation method of parameters in the numerical model and the servo function is optimized. Analyzed the linear contact model in the particle contact rigidity and particle microscopic parameters such as coefficient of friction on the initial elastic modulus, bulk modulus and the influence law of peak intensity. Suggestions value range of particle friction coefficient for large size specimen, wide grading condition of numerical experiments. For the study of scale effect provides the basis on selecting parameters.Four kinds of scale method is used and five scale biggest particle size as control condition for scalling original grading to analysis coarse-grained material mechanical properties before and after scalling. Levels of the original ingredients and scale of ingredients biaxial shear numerical tests have been carried out respectively. The influence of maximum particle size and reduced scale methods on the strength and deformation characteristics of coarse-grained soil was be studied. A power function expression of initial elastic modulus and Rd and another power function expression of initial bulk modulus and Rd were established respectively. Analysis the influence of Rd with Duncan EB model parameters K and Kb values. A method to calculate the Duncan EB model parameters of original grading coarse-grained soil through triaxial compression test results of scaled coarse-grained soil was suggested.