Study On The Influence Of Particle Morphology On Shear Fracture Mechanical Properties Of Coarse Grained Soils

Coarse-grained soil has many excellent engineering characteristics,so it is often used as a natural roadbed or filling material in engineering construction.Structure is one of the fundamental factors that affect the shear strength of coarse-grained soil.Research and analysis of the change characteristics of the shear strength of coarse-grained soil with the morphological structure of the soil body reveals the law of damage evolution of the soil particles during the shear process The mechanical properties and stability evaluation of granular soil have important guiding significance.This This paper discusses the shear strength characteristics of coarse-grained soils with different particle morphological structures and the evolutionary rules of particle breakage during shearing: by improving the traditional conventional direct shear apparatus,a visually transparent shear box is designed,and then the The granular soil particles were subjected to an indoor direct shear test.The high-definition digital camera was used to obtain the image data of the soil structure changes during the direct shear test.Then,with the help of image analysis software such as Matlab and Image Pro Plus,the research was conducted from the aspects of soil particle morphology and structural fractal characteristics,focusing on This paper discusses the breaking and evolution law of three types of coarse-grained soil under300 kpa normal stress.Finally,the particle flow discrete element software(PFC2D)is used to establish the corresponding numerical model of the direct shear test.The deep influence mechanism of the shear fracture characteristics of granular soil.The main research contents are as follows:(1)By summarizing previous research results and combining the morphological and structural characteristics of natural coarse-grained soil,the corresponding description and evaluation based on the characteristics of particle shape,particle size,particle angle and particle surface texture are carried out,and then the The structure types of coarse-grained soil were divided,and three samples of coarse-grained soil with three typical particle shapes were obtained.(2)The three types of coarse-grained soil samples were selected to carry out the visual indoor direct shear test under different normal stress conditions,mainly to explore the mechanism of the influence of the particle shape on the shear damage mechanical characteristics of the coarse-grained soil.(3)Combine with Matlab,Image Pro Plus and other image analysis software to identify and process the structural images of the soil at different shearing moments during the indoor direct shear test,extract the corresponding particle morphological parameters and perform statistical analysis,and then shear The crushing characteristics of coarse-grained soil samples with different particle morphology during cutting were studied in depth;combined with Matlab algorithm,the fractal dimension of deformation and crushing of soil structure during shearing process was analyzed,which further revealed the particle morphology on coarse-grained soil The law of fractal change in shearing and breaking.(4)using the discrete element numerical simulation software(PFC2D)particle flow on indoor direct shear test to carry out the simulation work,mainly on three particle shape coarse grained soil specimen under the condition of normal stress role at all levels of crack formation and evolution characteristics of carried on the thorough analysis,and from the Angle of grain contact force of coarse grained soil specimen system is analyzed.