Analysis Of Dynamic Characteristics Of Earth And Rock Mixture Based On Discrete Element Method

The earth-rock mixture as a kind of engineering materials more and more widely used in civil engineering, water conservancy and transportation and other Basic engineering fields. Earth-rock mixture is a discrete dielectric structure, composed of coarse and fine particle, having certain gradation and certain cohesiveness so its physical and mechanical properties is hard to grasp. Currently apply numerical method to the study of dynamic characteristics of earth-rock mixture can find few literatures. Under external force, it is difficult to analyze to use the finite element method requiring continuous displacement and stress because the earth-rock particles may produce sliding, rolling, flexing, crush and other phenomenons. Discrete element method provides an effective way in the this study issue to study the interaction between vibrating machinery and soil stone particles, forced vibration of particles, excitation response of particles and accumulation behavior of particles. Based on current research actuality with the Yanshan Reservoir in Henan as engineering background and based on the discrete element method study the dynamic characteristics of the earth-rock mixture. The main research contents and relevant conclusions are as follows:(1)The basic principle of the three-dimensional discrete element method is described, the basic idea of discrete element method, physical model, contact constitutive model and determining method of calculation parameter containing stiffness, damping, time-step etc are detailed and the discrete element method for the selection of parameters and its impact on calculation is discussed in-depth.(2) The modeling process using particle discrete element method is analysed, and generation of the particle, the set of the boundary conditions, the formation of the balance and stability of particle and the final formation process of particle are studied.(3) FISH language applied, generate randomly using Monte Carlo method for the three-dimensional particle discrete element simulation program, the PFWD (Portable Falling Weight Deflector short PFWD) dynamic numerical simulated acting on the soil, compared the simulation results with the measured results with PFWD and found that simulated values are very close, thereby verify the correctness of the program.(4) The influence of the microscopic parameters such as particle density, stiffness, bond strength, as well as the porosity to the delay, the peak, the pulse width of deflection curve and the stress curve is studied. According to different affecting factors containing particle density, stiffness, bond strength, as well as the porosity, four models are established, the microscopic parameters on the macro-dynamic response are analysed and the corresponding conclusions are drawed to use PFWD on the construction quality control of earth-rock mixture.The research results reveal the influence mechanism of microscopic parameters of earth-rock mixture on the macro-dynamic response, provide theoretical basis for the further developing the rapid detection indicators containing water content, compaction characteristics and others of earth-rock mixture and provide reference for dynamic mechanical behavior of earth-rock mixture.