时—温效应下膏体流变参数及管阻特性

发布时间：2018-05-21 11:00

本文选题：膏体充填 + 管道输送　；参考：《北京科技大学》2018年博士论文

【摘要】：膏体充填技术是国家“绿色矿山,深部采矿”发展战略的重要支撑,管道输送是优质膏体顺利进入采场实现预定功能的必要条件。通过流变学理论对结构流膏体的管道阻力特性进行分析是行之有效的方法。但膏体流变学特征与材料特性之间的关系以及在时间和温效应下的流变特征变化规律仍不清晰,同时在时-温效应下的膏体管道输送阻力也有待研究。从膏体材料的基本结构和性能出发,开展了流变参数影响因素实验与理论研究,建立了考虑时-温效应的膏体流变参数预测模型和时-温效应下的膏体管道输送阻力预测模型,并最终将理论成果成功应用于矿山充填实践。主要研究内容包括以下几点:(1)探明了流变参数随料浆浓度、膏体稳定系数和骨料比重的变化规律。构建了表征浆体级配结构的膏体稳定系数,从宏观、细观、微观三种尺度揭示了流变时-温演化机理。得出流变参数主要受料浆级配结构和絮网结构支配,触变过程是絮网秩序化的反映,温度升高促使絮网结构向液网结构转化,在流体曳力作用下絮网运移秩序化,屈服应力和塑性黏度降低。(2)建立了屈服应力和塑性黏度时-温效应计算模型。根据膏体料浆应力松弛特性建立了考虑剪切速率和时间因素的触变特征定量描述方法。首次对膏体触变性和温度效应进行了耦合分析,得出了屈服应力和塑性黏度随剪切时间和温度的变化规律。根据时-温等效原理建立了屈服应力和塑性黏度时-温效应预测模型。(3)综合考虑物料特性、输送条件和外部条件对膏体管道沿程阻力的影响,构建了时-温效应下膏体沿程阻力预测模型。得到了六种管道布置形式下的阻力变化特征。建立了时-温效应充填倍线计算方法,并量化了易发堵管、爆管事故的关键管段。(4)构建了时-温效应膏体管道输送数值模型,成功再现了时-温效应下膏体三维结构流态时空演化过程。通过离散具有时间和温度因子的Navier-Stokes(N-S)方程,计算得出了随时间和温度变化的膏体管道输送速度、压力分布规律。验证了数学模型的有效性。
[Abstract]:Paste filling technology is an important support for the development strategy of "green mine, deep mining" in China. Pipeline transportation is the necessary condition for the smooth entry of high quality paste into the stope to realize the predetermined function. It is an effective method to analyze the resistance characteristics of structural plaster by rheological theory. However, the relationship between rheological characteristics of paste and material properties and the variation of rheological characteristics under time and temperature effects are still unclear, and the resistance of plaster pipeline transportation under time-temperature effect is also to be studied. Based on the basic structure and properties of the paste material, the experimental and theoretical study on the influencing factors of rheological parameters was carried out, and the prediction model of rheological parameters of the paste considering the time-temperature effect and the resistance prediction model of the plaster pipeline transportation under the time-temperature effect were established. Finally, the theoretical results are successfully applied to the practice of mine filling. The main contents of this study are as follows: (1) the variation of rheological parameters with slurry concentration, paste stability coefficient and aggregate specific gravity is studied. The stability coefficient of paste was constructed to characterize the structure of slurry gradation, and the mechanism of rheological time-temperature evolution was revealed from macroscopic, meso and microscopic scales. The rheological parameters are mainly controlled by slurry gradation structure and floc net structure, and the thixotropic process is the reflection of the order of the floc net, and the increase of temperature promotes the transformation from the floc structure to the liquid net structure, and the floc movement is orderly under the action of the fluid drag force. The yield stress and plastic viscosity are reduced. 2) the time-temperature effect model of yield stress and plastic viscosity is established. According to the stress relaxation characteristics of paste slurry, a quantitative description method of thixotropic characteristics considering shear rate and time was established. The thixotropy and temperature effect of paste were analyzed for the first time, and the variation of yield stress and plastic viscosity with shear time and temperature was obtained. According to the principle of time-temperature equivalence, a prediction model of yield stress and plastic viscosity time-temperature effect is established. The prediction model of the resistance along the paste under the effect of time and temperature was established. The variation characteristics of resistance under six types of pipeline arrangement are obtained. The calculation method of time-temperature effect filling doubling line is established, and the numerical model of pipeline transportation of time-temperature effect paste body is established by quantifying the key section of pipe that is easy to be plugged and the key section of pipe burst accident. The spatiotemporal evolution of the three-dimensional structure of the paste under the time-temperature effect has been successfully reproduced. By discretization of Navier-Stokes N-S equation with time and temperature factors, the distribution of velocity and pressure of plaster pipeline with time and temperature is calculated. The validity of the mathematical model is verified.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2018
【分类号】：TD853.34

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