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Evolution of Contact Shear Resistance and Arching in Silica Sand

硅砂接触剪切阻力和起拱的演变

基本信息

批准号：
1901582
负责人：
Radoslaw Michalowski
金额：
$ 45.88万
依托单位：
Regents of the University of Michigan - Ann Arbor
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1901582&HistoricalAwards=false
关键词：
Evolution Contact Shear Resistance Arching

项目摘要

The time-dependent behavior of granular geomaterials is among the least understood of their characteristics, and arching in granular materials is an elusive phenomenon without the definitive mathematical framework needed for engineering analyses. This research addresses time-dependent evolution of contacts between silica sand grains, with its consequences on strength, stiffness, and arching formation in sand. This study seeks to discover microscopic processes which govern the behavior of soils. A link between evolution of inter-grain contacts and arching in granular geomaterials is sought, with a goal of a more informed use of arching in engineering analyses. The twofold purpose of the study is in promoting progress in science, and in benefits to society stemming from application of the research results in the development of national infrastructure. Behavior of soils is typically described by phenomenological models that predict their response to loads and load duration on the engineering scale. These models, however, do not explain the physical cause of the behavior they describe. In order to exercise any influence over the material behavior, the origin of the behavior needs to be discovered. This research addresses the fundamental question of why silica sand contacts exhibit time-dependent behavior that leads to time-dependent evolution of contact shear resistance and stiffness. A new generation of grain-scale testing apparatus will be constructed to test grain contacts subjected to complex loads. Testing of contacts will give rise to a mathematical description of contact behavior, which, subsequently, will be upscaled to the networks of grain contacts, and to the engineering scale behavior. The influence of the evolution process of material properties that originates at inter-grain contacts on formation of internal arches in soil masses will be studied. Both the distinct element approach and finite element analysis will be carried out to gain insight into the elusive phenomenon of arching in granular materials. The outcomes of the research will be illustrated with engineering applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

粒状岩土材料的时间依赖性行为是人们对其特性了解最少的一种，粒状材料中的膨胀是一种难以捉摸的现象，没有工程分析所需的明确的数学框架。这项研究解决了石英砂颗粒之间的接触随时间变化的演变，其后果的强度，刚度，并在砂中的结晶形成。这项研究旨在发现控制土壤行为的微观过程。寻求颗粒间接触的演变与粒状地质材料中的成拱之间的联系，目标是在工程分析中更明智地使用成拱。这项研究有两个目的，一是促进科学进步，二是将研究成果应用于国家基础设施的发展，使社会受益。土的特性通常由现象学模型描述，该模型预测土对工程规模上的荷载和荷载持续时间的响应。然而，这些模型并不能解释它们所描述的行为的物理原因。为了对物质行为施加任何影响，需要发现行为的起源。这项研究解决了为什么硅砂接触表现出时间依赖性的行为，导致时间依赖性的接触剪切阻力和刚度的演变的基本问题。新一代的颗粒尺度试验装置将被建造来测试承受复杂载荷的颗粒接触。接触测试将产生接触行为的数学描述，随后将升级到晶粒接触网络和工程规模行为。将研究起源于粒间接触的材料性质的演化过程对土体内拱形成的影响。离散元方法和有限元分析将进行深入了解颗粒材料中的难以捉摸的现象。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。