Research On Meso-structure Characteristics And Mechanical Properties Of Accumulated Or Deposited Soil-rock Mixture Based On Discrete Element Method

Accumulated soil-rock mixture is a loose mixed system consisting of high-strength block stones and soil particles with relatively weak strength.It has a high degree of inhomogeneity and discontinuity,and its macro-mechanical properties mainly depend on its meso-structure characteristics,its meso-structure characteristics are closely related to the blocks in the mixed system.In order to deeply study the meso-structure characteristics of soil-rock mixture and its influence on mechanical properties,and further reveal the internal mechanism of deformation,a triaxial test random discrete element model was established,The sensitivity parameters of the mesoscopic parameters in the model were analyzed,and the correlation parameters were inspected and verified in conjunction with the results of the indoor large triaxial tests.On this basis,the investigation of the meso-structure characteristics of soil-rock mixture under two typical geological environments and the analysis of the mechanical characteristics of the factors affecting the meso-structural characteristics of the soil-rock mixture are carried out.The main conclusions are as follows:(1)The susceptibility analysis of the normal contact grain stiffness,tangential contact stiffness,normal bond strength of soil particles and tangential bond strength meso-parameters in the triaxial discrete element model of soil-rock mixture are performed.It is found that the effect of the above mesoscopic parameter change on the macroscopic deviatoric stress and body strain of the soil and rock sample was obtained.(2)Based on the meso-scale parameters after calibration,the meso-structure characteristics of soil-rock mixture under the environment of horizontal consolidation and slope deposition environment were explored using the discrete element method,and the differences in the meso-structure of the soil-rock mixture under the two geological environments were found.The distribution of the meso-structure of the soil-rock mixture in the two geologic environments was obtained.(3)The factors such as the orientation angle of block stone,the ratio of the length and the minor axis of block stone,the grain size of block stone,the gradation of rock,etc.will have a certain influence on the meso-structure of soil-rock mixture.The effects of the above factors on the mechanical properties and deformation characteristics of soil and rock are discussed.The stress-strain and volumetric curves of soil and rock were obtained,and the variation of shear strength of soil-rock mixture with the above factors was obtained.(4)Through multivariate linear regression analysis,the contributions of factors such as orientation angle of block stone,ratio of length and short axis of block stone,grain size of block stone,and non-uniform coefficient to the shear strength of soil-rock mixture were obtained.It can provide certain guiding significance for related projects and slope management issues.