Numerical Simulation Of Triaxial Shear Test Considering Particle Breakage

When quartz sand is used as foundation material,it is usually at a certain depth underground and under great stress.At this time,particle breakage often occurs in quartz sand material,which affects the mechanical and deformation characteristics of quartz sand and has an important influence on the design of engineering structure.At present the study of particle breakage mainly through laboratory test and numerical simulation of two kinds of methods,in which there are two main types of numerical simulation of particle breakage model,particle binding model and fragments replacement model respectively,and the two model can partly reflect the sample under the influence of particle breakage deformation characteristics and the change trend of strength characteristics.And sand the critical state of research on all kinds of building foundation safety is very important,but the existing fragments substitution method of numerical simulation method,the particle breakage,the volume of the sample will be cut,because of the problem of algorithm to measure the void ratio is not accurate,according to the above problem in this paper,the main research contents and conclusions are as follows:Through the current use of particle flow software to take into account the particle fragmentation of the simulation method to improve.Aiming at the loss of particle volume in the process of replacement in the debris replacement method,small particles of the same volume are used to replace the broken particles.For smaller radius of circular particles such as volume,if its in the original position of particles generated in the,will and not broken particles around a lot of overlap,in the interior of the sample for the introduction of a large contact force,in order to eliminate the unreasonable overlap,the article using particle flow software alone exposure guidelines,in does not affect the premise of triaxial loading process,the unreasonable overlap,at the same time the new generation of particles in the loading triaxial specimen,substitution method to overcome the existing debris caused by algorithm of sample volume reduction.using the method of substitution of debris such as volume,based on Hertz contact model of Hertz modulus of three parameters,friction coefficient,poisson’s ratio on the strength characteristics and deformation characteristics of simulation sample,the influence of the different modulus of Hertz(hz modulus are: 5.5 e5,9 e5,13 e9)under three groups of simulation experiment,the different friction coefficient(friction coefficient are: 0.4,0.6,0.9),the three groups of simulation experiment was carried out,in different poisson’s ratio(poisson’s ratio are: 0.01,0.1,0.2)three sets of simulation experiment was carried out.Finally,the influence of Hertz modulus,friction coefficient,poisson’s ratio on the deviatoric stress,volume change and Br value of crushing indexes of the sample was determined.The parameters were further compared with the laboratory results to determine the parameters of the model.using the data obtained by calibrating with the laboratory experimental data,the test sample was designed with multiple pore ratios and confining pressures to control whether the test sample could be broken in the loading process.A total of 32 tests were conducted.The strength characteristics and deformation characteristics of the samples affected by particle fragmentation,as well as the development law of the anisotropy of the samples were investigated.At the same time,the phenomenon of specimen shrinkage softening and dilatation hardening was explained from the perspective of the number of contacts between particles and the average contact force.using the soft particle flow software can be any time in the loading process of sample of each and every particle position displacement such as microscopic observation,analysis of the sample without coaxial get dint chain and the position of the crushing particle distribution,combining macroscopic strength characteristics,sample analysis under the influence of particle breakage sample micro state,further explain the macro properties from the microscopic view.At the same time,by using the characteristic that the particle volume will not be lost in the process of this method,it can be further concluded that the pore ratio related data obtained by the model when considering the particle fragmentation is closer to the real situation,and the deformation characteristics related to the pore ratio and the change of the critical state line of the sample are not analyzed.