碎石颗粒形状评定及其对碎石料渗透性影响的初步研究

发布时间：2018-06-25 10:17

本文选题：颗粒形状 + 形状参数　；参考：《长江科学院》2015年硕士论文

【摘要】：多孔介质是由固体构成复杂孔隙系统的骨架,流体可以在其内部连通的孔隙系统运动的物质空间。最常见且为人们广泛利用的多孔介质固体材料为人工爆破碎石料或经过长距离搬运的砂砾石,所以研究颗粒形状对于多孔介质孔隙系统和渗透特性的影响,具有重要实际意义。本文研究颗粒形状的测量途径和评价方法,采用影像测量仪和专门研制的夹具,利用5个形状参数对三组粒径的颗粒形状进行测量和评定。通过利用CT机扫描获取的扫描断面图,在不同开度阈值下统计分析了碎石料填筑试样和玻璃球填筑试样孔隙大小分布规律,以及孔隙形状分形特征。通过碎石料和玻璃球填筑试样的渗透试验,初步分析探讨了颗粒形状对多孔介质渗透特性的影响规律。本文的主要研究内容和结论如下:(1)采用影像测量仪和专用夹具多角度量测碎石颗粒形状,丰富了颗粒形状测量信息,为更准确地评定颗粒形状奠定了基础。(2)采用5个形状参数评定颗粒形状。统计分析了三个粒径组颗粒群的形状参数分布规律,获取颗粒形状参数的分布特征,比较碎石颗粒与标准球体形状的差异。通过形状参数的对比,指出长宽比、扁平度和球形度能够较敏感地反映颗粒偏离球体的程度,其中,相对于扁平度来说,长宽比、球形度的获取更方便和直接,因而在可操作性和效率上更具优势。(3)利用CT机扫描获取碎石料和玻璃球填筑试样的断面图,发现其内部的孔隙形态都很复杂,所选粒径组试样CT扫描二维图像上显示了较好的连通性。采用合适的孔隙开度阈值,可以在狭窄处断开孔隙,以便开展孔隙大小统计分析和分形特征研究。(4)针对同一粒组同一粒径分布的碎石颗粒和玻璃球填筑试样,可以开展渗透性对比试验,初步结果表明,颗粒形状越不规则,渗透系数越大。
[Abstract]:Porous media is a material space in which a complex porous system is composed of solids, in which fluid can move through a connected pore system. The most common and widely used solid material in porous media is artificial blasting gravel or sand gravel which is transported over long distances. So it is of great practical significance to study the influence of particle shape on pore system and permeability characteristics of porous media. In this paper, the measurement and evaluation methods of particle shape are studied. The shape of three groups of particle size is measured and evaluated by using the image measuring instrument and the specially developed fixture, using five shape parameters. The pore size distribution law and fractal characteristics of pore shape of gravel filled specimen and glass ball filled specimen were statistically analyzed under different opening threshold by using scanning sectional diagram obtained by CT scanning. The influence of particle shape on permeability characteristics of porous media was preliminarily analyzed through the permeation test of gravel and glass ball filled samples. The main contents and conclusions of this paper are as follows: (1) the shape of crushed stone is measured by image measuring instrument and special fixture, which enriches the information of particle shape measurement. It lays a foundation for more accurate evaluation of particle shape. (2) five shape parameters are used to evaluate particle shape. The distribution rules of shape parameters of three particle groups were statistically analyzed, and the distribution characteristics of particle shape parameters were obtained, and the differences between gravel particles and standard spheres were compared. Through the comparison of shape parameters, it is pointed out that the aspect ratio, flatness and sphericity can more sensitively reflect the degree of particle deviation from the sphere, and the ratio of length to width is more convenient and direct to obtain the spherical degree than the flatness. Therefore, it has more advantages in maneuverability and efficiency. (3) using CT scanning to obtain the fracture diagrams of gravel and glass-filled specimens, it is found that the internal pore morphology is very complex. The two-dimensional CT images of the selected particle size groups showed good connectivity. With the appropriate pore opening threshold, the pores can be disconnected in the narrow area for the purpose of statistical analysis of pore size and study of fractal characteristics. (4) for the sample filled with crushed stone and glass ball with the same particle group and the same size distribution, The preliminary results show that the more irregular the particle shape, the greater the permeability coefficient.
【学位授予单位】：长江科学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU411

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