Study On The Rock Particle Crushing Using Discrete Element Method

Rock particles are commonly used in engineering projects and widely studied by academia and industry.Discrete element method can cover the shortage of the traditional continuum theory and simulate the complex motion of the rock particle system effectively.The fractal theory is combined with geotechnical engineering projects to analyze the particle crushing of rock,using discrete element method in this paper.The main contents of this paper are as follows:(1)PFC2D software is used to simulate Brazilian test on a single rock particle with the different porosity.The method to set the initial porosity is introduced by describing the algorithm to add or delete particles in detail.The crushing procedure of a single rock particle is given with the crack's development law.The algorithm to obtain the particle size distribution of rock fragments is given by defining the judgment rule of a rock fragment.The fractal dimension are 2.58,2.73 and 2.85 while the porosity of the single rock particles are 0.25,0.15 and 0.10.The fractal dimension decreases with the porosity increasing,which verifying the fractal theory of the crushing strength of the single rock particle.The crushing probability of sing rock particles with the different porosity are analyzed to obtain the relationship between the crushing probability and the crushing strength,which verifying the modified Weibull theory.The fractal dimension is obtained by analyzing the crushing energy and the results match well with that given by the particle size distribution.(2)PFC2D software is used to simulate the direct shear tests of rockfill materials considering the particle crushing.Several classical theories of the shear strength of rockfill materials are introduced and verified by results obtained from the numerical simulation.The methods to establish the model of the rockfill sample and conduct the tests are given.The results obtained from the numerical simulation are analyzed from several aspects,such as the characteristics of macroscopic stress and volume strain,rock material's shear strength and broken rate,and the change of the contact force chains.The contact-bond strength between basic particles,the porosity of the single rock particle and the porosity of the rockfill material are discussed to study their influence to the shear strength of the rockfill sample.