Automating particle size and shape measurement in soil mechanics

已经确定的是，单个颗粒的几何形状（大小和形状）影响颗粒材料对施加载荷和变形的整体响应。传统土力学中，我们通过一系列孔径不同的筛子来测量土颗粒的大小。通过将少量颗粒的形状与标准（2D）图表进行比较，对形状进行定性测量。这些方法有一些缺点。考虑筛分，我们没有关于标准筛分间隔之间粒度分布的信息。筛子分析的结果并不总是一致的，特别是当涉及到长片状颗粒时。粒度分布的变化被用来评估对单个颗粒的损害，我们需要测量的微小变化不能用筛分析可靠地检测到。关于形状分析，我们知道颗粒材料中的颗粒是三维的。我们还知道，要对颗粒材料中的颗粒形状和颗粒形状变化进行统计上有效的评估，必须考虑成千上万个颗粒的形状。传统的简单、直观的粒子几何描述不允许对有统计意义的粒子数量进行客观、定量、三维的形状分析。Sympatec公司生产的QicPic仪器是一项新技术，它包括一个分散颗粒的系统，一个高速相机和复杂的图像分析软件来测量颗粒的大小和形状。该仪器克服了传统低技术方法的局限性，允许对大量颗粒的大小和形状进行3D评估。我们可以使用这个仪器，它被安装在我们的实验室里，进行了一周的试验。在此期间，我们确定了该仪器可以对我们感兴趣的粒子产生有效的测量，它可以很容易地被我们的研究生使用，并且输出的复杂程度（包括单个粒子的黑白图像）使其成为粒子形态学基础研究的好工具。这台仪器将提高我们在质量控制方面的能力，使我们能够进行一系列涉及颗粒材料的实验工作。这些材料包括用于土壤力学研究的天然和人工砂，用于生物医学工程研究的碎骨，以及用于环境工程研究的从废物副产品中开发的人工骨料。该装置还可以用来更好地了解当颗粒材料加载和变形时单个颗粒是如何受损的，这种理解对于开发材料的数值模型非常重要。该装置也将有助于支持正在进行的研究，这些研究将发展整体材料响应与组成粒子特性之间的关系。申请者已经在合作开发量化颗粒强度和颗粒几何形状的方法，并将这些特征与整体材料响应联系起来。我们目前的设备包括光学显微镜，表面测绘显微镜和单粒子机械装置。这一机构将补充这些工具，并加强我们在这一领域的专门知识。

It is well established that the geometry (size and shape) of the individual particles influences the overall response of a granular material to applied loads and deformations. Traditionally in soil mechanics we measured the size of soil particles by passing the particles through a succession of sieves with different aperture sizes. Shape was measured qualitatively, by comparing the shape of a small number of particles with standard (2D) charts. These methods have some disadvantages. Considering sieving, we have no information about the distribution of particle sizes between the standard sieve intervals. The results of a sieve analysis are not always consistent, especially when long platy particles are involved. Changes in particle size distribution are used to assess damage to the individual particles, and the small changes we need to measure cannot be reliably detected using a sieve analysis. Regarding shape analysis, we know that particles in granular materials are three-dimensional. We also know that to get a statistically valid assessment of particle shape and particle shape variation in a granular material, the shape of thousands of particles should be considered. The traditional simple, visual description of particle geometry does not allow objective, quantitative, three-dimensional shape analysis of statistically meaningful numbers of particles. A new technology, the QicPic apparatus manufactured by Sympatec, includes a system for dispersing particles, a high speed camera and sophisticated image analysis software to measure particles sizes and shapes. This apparatus overcomes the limitations of the traditional low tech approaches, allowing 3D assessment of size and shape for large numbers of particles. We have had access to this apparatus, it was installed in our laboratory for a one-week trial period. During this period we established that the apparatus can produce valid measurements for the particles we are interested in, it can easily be used by our research students, and the degree of sophistication of the output (including black and white images of individual particles) makes it a good tool for fundamental research on particle morphology.This apparatus would provide us with improved capabilities for quality control for a range of experimental work involving granular materials in the department. These materials include natural and artificial sands used in soil mechanics research, morsellised bone used in biomedical engineering research and artificial aggregates that are being developed from waste by-products as environmental engineering research. The apparatus can also be used to better understand how the individual particles are damaged when a granular material is loaded and deformed, and this understanding is important for developing numerical models of the material. The apparatus would also be useful to support ongoing research that will develop a relationship between the overall material response and the characteristics of the constituent particles.The applicants are already collaborating to develop methods to quantify both particle strength and particle geometry and relate these characteristics to the overall material response. Our current facilities include an optical microscope,a surface mapping microscope, and single particle mechanical apparatii. This apparatus would complement these tools, and strengthen our expertise in this area.