Based On The Particle Flow Discrete Element Of Blast Furnace Slag And Fly Ash Mixture Of Micro Mechanics Characteristic Research

Based on the particle flow discrete element numerical software PFC3D, a simplifiedmodel of lab large-scale direct shear test was established through the secondarydevelopment Fish language. Through analysing the correlation of sample macro-microparameters, and the simulation values and the test values was compared, determine thefinal micro input parameters of numerical model by the calibration process. Finally, thestudy on the effects of numerical test conditions to the mixture of shear strength wasconducted, respectively from the mechanical response, energy response and fieldchange three aspects; In addition, the empirical proportion was optimized, the reliabilityof the empirical proportion was verified, and selected the optimal mix proportion.PFC3D, as a method to study the discrete medium, can accurate simulate the directshear test process of blast furnace slag fly ash mixture, and it has high reliability, shortcycle and low cost. Through analysing the influence of the particle friction coefficient,stiffness ratio, strength ratio and radius factor on the peak strength, the initial elasticmodulus and strength parameters, the effective range of micro parameters of specimenswas obtained. On this basis, the sample final micro parameters was calibrated, and thedirect shear test of the numerical models was accurate established. Based on the existingnumerical model, the48groups of mixture samples large direct shear tests was carriedout. By changing the loading rate, porosity and coarse grain content under differentconfining pressure experiment, the optimal loading rate, porosity and the optimalcontent of coarse particles were determined from the angle of mechanical response,energy response and contact force chain field, which can provide reference forengineering application. Based on analysis of the development trend of sheardisplacement field and change rule, measurement ball’s horizontal displacement wassupervised along the shear box height setting through the Fish language of the PFC3Dwriting code. By calculating, the width of shear band of mixture L is60.75mm, whilethe samples average diameterD30is30mm, that is L=2D30. Based on optimizationanalysis of the mixtures mix ratio, the experience mix ratio5:1is reliable but not the best mix proportion; the result of mixture mechanical response, energy response and thecontact force chain field are best ideal When the mix ratio is4:1, so4:1is considered asthe best mix proportion.Blast furnace slag, which is a typical discrete medium, the physical and mechanicalof properties was complex. By using the model of finite element discretization and theconventional laboratory tests, it is difficult to reveal the complex mechanicalcharacteristics and damage mechanism in essence. Therefore, based on the theory of thethree-dimensional particle flow discrete element, the research of blast furnace slag flyash mixed material micro mechanical properties has important theoretical value andpractical significance.