Numerical Simulation Of Mechanical Properties Of Graded Crushed Rock Based On Discrete Element Method

Graded crushed rock,which is made of a variety of materials,is a granular,discrete multi-phase system with good force dispersion ability.At present,the research on the mechanical properties of graded crushed rock,macadam is becoming more and more perfect at the macroscopic level.However,at the micro-level,the mechanical properties of the graded crushed rock are much less clear,and it's diffieult to reveal the microcosmic properties of graded crushed rock with the continuum mechanics theory or the indoor experiments.Therefore,this paper intends to use then umerical simulation based on discrete element in combination with indoor tests to study the micro-mechanical properties of graded crushed rock.The type of the graded crushed rock is determined according to the grading scale of graded crashed rock,in our country as well as to the construction technology of reality.The maximum dry density and the optimum moisture contentof the gravel material are determined by the heavy compaction test.Its CBR value and shear strength indexes are obtained through the CBR and triaxial shear tests.The virtual graded crushed rock was produced by using the FISH language of the discrete element soffware PFC3D.Then the three-dimensional CBR and three-axis shear numerical simulation models were established.The micro-mechanical parameters of the graded crushed rock particles were acquired by analyzing its CBR and the three-axis shear numerical simulation models.The results show that the propagation of the load is mainly carried out by the skeleton in the CBR test,and the particles penetrating into the rod are concentrated in the vicinity of the particle,but the outer and bottom particles are less affected.In the triaxial shear test,the internal particles form a dynamic equilibrium system by adjusting and affecting each other on the influence of external force.The main chain face is less affected by the particles on the vertical surface and its angle with the horizontal plane remains unchanged in the process of its impact.The effects of micro-mechanics parameters on the numerical simulation of CBR and triaxial shear test are analyzed.The influence intensity of micro-mechanic parameters on micro-CBR and triaxial shear tests can be ordered as follows:The order of influence intensity of micro-mechanics parameters on CBR is:normal stiffness>friction coefficient tangential stiffness>normal bond>tangential bond;The order of influence intensity of micro-mechanics parameters on shear strength is:normal bond>tangential bond>friction coefficient>tangential stiffness>normal stiffness;...