Research On The Constitutive Model Of Soil-rock Mixture And Its Application On Slopes

Soil-rock mixture(SRM)is an important kind of geomaterial that is widely distributed in nature and often used as construction materials.Besides,the natural slopes of SRM usually have large potential landslide hazard.Hence,the research on the mechanical characteristics of SRM and the SRM slope stability is of great significance to ensure the stability of construction project.Due to the large differences in structural size and mechanical property of the soil and rock blocks of SRM,the mechanical characteristics of SRM is complex and influenced by various factors,and the relevant elastic-plastic constitutive models with clear physical meanings are seldom published.Through the physical tests,this article investigated the mechanical characteristics of SRM,revealed the block function mechanism,built an elastic-plastic constitutive model that was applicable to SRM and realized the numerical calculation based on the model.The main conclusions obtained are as follows.(1)This article conducted a series of plane strain tests on SRM with the blocks simulated by gravels and aluminum rods and summarized the main macroscopic physical characteristics of SRM.Besides,this article revealed that the main influence factors on the mechanical characteristics of SRM were block content,block shape and block distribution.Based on the analysis of block motion during the tests,it was found that the rotation not the translation of blocks was the main microscopic motion factor that influenced the mechanical characteristics of SRM.This article put forward a microscopic block parameter---the effective block content to synthesize the main influence factors.(2)This article selected CSUH model as the framework and introduced two new parameters termed as “yield ratio” and “reduction factor of void ratio” respectively to derive the critical state and the yield characteristics as the block content and block function varied,in order to build a constitutive model that was applicable to SRM.This article compared the results of the plane strain tests and verified the model,and described the method of determining parameters and the application range of the model.(3)This article conducted a series of centrifugal model tests on SRM slopes.Based on the test results,this article revealed the change law of the macroscopic responses of SRM slopes and the microscopic motion of blocks when the block content varied.It was the rotation not the translation of blocks that mainly influenced the failure of SRM slopes.The blocks in the sliding body could also form a chain to bear the load and change the displacement distribution of the adjacent matrix sands through the block rotation.(4)This article realized the numerical simulation method of the SRM structures by building the Abaqus subprogram based on the elastic-plastic constitutive model of SRM,and the centrifugal model tests and a practical engineering project were simulated by this method.The comparison between the numerical simulation and the physical tests verified the effectiveness of the method and revealed the response of the shear stress level and the maximum and minimum principle stress,and analyzed the development law of the stress and deformation in SRM slopes furthermore.