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The Application of Micro-Mechanical Research on Coarse Grained Soils to Create an "Avatar" Railway Ballast

应用粗粒土微力学研究打造“阿凡达”铁路道碴

基本信息

批准号：
EP/S026460/1
负责人：
Matthew Coop
金额：
$ 115.63万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FS026460%2F1
关键词：
Application Micro Mechanical Research Coarse

项目摘要

The engineering analysis of geotechnical structures such as building foundations, tunnels or embankments, is usually made assuming that the soil acts as a continuous material, as if it were, for example, a metal. The tests that we carry out to characterise soil therefore utilise samples that have a representative number of particles, often millions, within them. The problem with this approach is that the soil behaviour is extremely complex, much more so than most other materials, resulting from the soil actually consisting of discrete particles with water filled voids between, and also the fact that these particles have a natural rather than man made origin, which can affect their shape, strength and arrangement. The extreme complexity of the equations we might use to characterise soil then means that our research understanding of soil behaviour is rarely fully implemented in engineering design. In recent years increased computing power has led to the increasing use of discrete approaches in the analysis of soils, in which individual soil particles are modelled. In such an analysis it is important to model accurately the key characteristics of the particles that will influence the overall behaviour of the soil mass; their shapes, strengths, the arrangement that they have relative to each other and how they behave when they touch. Advances have been made in all of these areas, with the exception of the particle contact behaviour, which in recent years has been the special interest of Professor Coop, who has developed a new apparatus with which to investigate this aspect. Having understood the contact behaviour, we will be in a good position to create a virtual or "Avatar" model of soil particles, at least for sands size and above, and this is the aim of this research. The vehicle for doing this is to address the practical engineering problem of modelling particles of railway ballast used to support rail track, the ballast in this sense being regarded as a large grained sand. Collaborating with noted experts on ballast behaviour at Nottingham University (Professor McDowell) and Southampton University (Dr. Zervos), and with contributions on soil particle shape description from Dr Baudet of UCL, the research will create a virtual model of several typical ballasts, capturing their shapes, arrangement, any damage that occurs during loading by the trains as well as, most crucially, the contact behaviour between particles. Such a model could then be used both in research and engineering design, but the first step will be to validate that it is successful. This can only be done by comparing the output of discrete numerical analyses using the model particles with "real events". The most convenient real events are "triaxial" tests, which are conventional continuum type tests in which a cylindrical sample of many particles is loaded and the response monitored. These are difficult tests and ultimately the aim of this type of research would be to render them obsolete as we then rely only on the new particle scale tests and modelling.

对土工结构的工程分析，如建筑基础、隧道或路堤，通常假定土壤是一种连续的材料，就像它是一种金属一样。因此，我们进行的表征土壤的测试使用的样本中含有具有代表性的颗粒数量，通常是数百万个。这种方法的问题是，土壤的行为极其复杂，比大多数其他材料要复杂得多，这是因为土壤实际上由离散的颗粒组成，中间有水填充的空隙，而且这些颗粒具有自然而不是人为的来源，这可能会影响它们的形状、强度和排列。我们可能用来描述土壤的方程极其复杂，这意味着我们对土壤行为的研究理解很少在工程设计中完全实现。近年来，计算能力的增强导致了在土壤分析中越来越多地使用离散方法，在这种方法中，单个土壤颗粒被建模。在这样的分析中，重要的是准确地模拟颗粒的关键特性，这些特性将影响土体的整体行为；它们的形状、强度、它们相互之间的排列以及它们接触时的行为。在所有这些领域都取得了进展，除了粒子接触行为，这是近年来Coop教授特别感兴趣的，他开发了一种新的仪器来研究这一方面。了解了接触行为后，我们将能够很好地创建土壤颗粒的虚拟模型或“阿凡达”模型，至少对于沙子大小和以上的土壤颗粒是如此，这就是本研究的目的。这样做的工具是为了解决实际的工程问题，即对用于支撑铁轨的铁路道碴颗粒进行建模，在这个意义上，道碴被视为大颗粒沙子。与诺丁汉大学(McDowell教授)和南安普顿大学(Zervos博士)的著名道碴行为专家合作，以及伦敦大学学院的Baudet博士在土壤颗粒形状描述方面的贡献，这项研究将创建几种典型道碴的虚拟模型，捕获它们的形状、排列、在火车装载过程中发生的任何损坏，以及最关键的颗粒之间的接触行为。这样的模型可以同时用于研究和工程设计，但第一步将是验证它是成功的。这只能通过将使用模型粒子的离散数值分析的输出与“真实事件”进行比较来实现。最方便的真实事件是“三轴”测试，这是传统的连续型测试，在这种测试中，加载包含许多颗粒的圆柱形样本，并监测响应。这些都是困难的测试，最终这类研究的目的将是使它们过时，因为我们那时只依赖于新的颗粒尺度测试和建模。