基于颗粒流离散元的高炉渣粉煤灰混合料细观力学特性研究

发布时间：2018-02-21 19:14

本文关键词： 大型直剪试验高炉矿渣粉煤灰颗粒流离散元力学特性　出处：《内蒙古科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文采用颗粒流离散元软件PFC3D作为数值分析平台，通过二次开发的Fish语言建立具有与室内试验相同的简化模型，，虚拟实现室内大型直剪试验。通过分析试样宏－细观参数间的相关性，标定数值模型最终的细观输入参数，进而对室内试验进行仿真对比。最后，分别从力学响应、能量响应以及场的变化三方面研究试验条件对混合料剪切强度数值试验的影响；对经验配合比进行优化，并验证其可靠性，同时选出最优配合比。 PFC3D作为研究离散介质的一种方法，它能够准确地模拟高炉矿渣与粉煤灰混合料的直剪试验过程，试验结果可靠性高、周期短且成本低。通过分析颗粒摩擦系数、刚度比、强度比及半径因子对峰值强度、初始弹性模量及强度参数的影响，得到了试样细观参数的有效取值范围。在此基础上，标定试样的最终细观参数，建立准确的室内大型直剪试验数值模型。基于已有的数值模型，对混合料试样共进行了48组大型直剪试验。试验中通过改变不同围压时的加载速率、孔隙率及粗粒含量，并从力学响应、能量响应以及接触力链场的角度进行分析，确定了最佳的加载速率值、孔隙率范围及最优粗粒含量，可为工程应用提供借鉴。在对剪切位移场的发展趋势和变化规律分析的基础上，通过PFC3D中的Fish语言编写代码，监测沿剪切盒高度设置的测量球水平位移。经计算得到，混合料的剪切带宽度L=60.75mm，而试样平均粒径D30=30mm，即L=2D30。通过对混合料的配合比进行优化分析得到，经验配合比5:1具有一定的可靠性但不是最优配合比；当配合比为4:1时，混合料的力学响应、能量响应及接触力链场的结果最为理想，认为是最优配合比。高炉矿渣作为典型的离散介质，其物理力学特性复杂，若采用有限元的离散化模型和常规的室内试验，难以从本质上揭示其复杂的受力特性和损伤机制。因此，本文基于三维颗粒流离散元理论，对高炉渣粉煤灰混合料细观力学特性研究具有重要的现实意义和理论价值。
[Abstract]:In this paper, the particle flow discrete element software PFC3D is used as the numerical analysis platform, and the simplified model with the same as the indoor test is established by the second developed Fish language. By analyzing the correlation between the macro and mesoscopic parameters of the samples, calibrating the final mesoscopic input parameters of the numerical model, and then comparing the simulation results of the laboratory tests, the mechanical responses are analyzed. The influence of test conditions on the shear strength of mixture is studied from three aspects: energy response and field change, and the empirical mixture ratio is optimized, its reliability is verified, and the optimal mixture ratio is selected. As a method to study discrete medium, PFC3D can accurately simulate the direct shear test process of blast furnace slag and fly ash mixture. The test results are high reliability, short period and low cost. The influence of strength ratio and radius factor on the peak strength, initial elastic modulus and strength parameters is obtained, and the effective range of meso-parameters is obtained. On the basis of this, the final meso-parameters of the sample are calibrated. An accurate numerical model of large direct shear test was established. Based on the existing numerical model, 48 groups of large direct shear tests were carried out on the mixture samples. The loading rate, porosity and coarse particle content were changed under different confining pressures. From the angle of mechanical response, energy response and contact force chain field, the optimum loading rate, porosity range and coarse-grain content are determined. It can be used as a reference for engineering application. Based on the analysis of the development trend and variation law of shear displacement field, the code is compiled by Fish language in PFC3D to monitor the horizontal displacement of the measuring sphere set along the height of the shear box. The shear band width of the mixture is 60.75mm, and the average particle size of the sample is D3030mm, that is, L2D30mm. Through the optimization analysis of the mixture mix ratio, the empirical mixture ratio of 5: 1 has certain reliability but is not the optimal mix ratio; when the mixture ratio is 4: 1, The results of mechanical response, energy response and contact force chain field of mixture are the most ideal, which is considered to be the optimal mix ratio. As a typical discrete medium, blast furnace slag has complex physical and mechanical properties. If the finite element discretization model and conventional laboratory tests are adopted, it is difficult to reveal the complex mechanical properties and damage mechanism of blast furnace slag in essence. Based on the three-dimensional granular flow discrete element theory, this paper has important practical significance and theoretical value for the study of the meso-mechanical properties of blast furnace slag and fly ash mixture.
【学位授予单位】：内蒙古科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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