The evolution of crushing in granular materials and its influence on their mechanical properties

粒状物料破碎的演变及其对其机械性能的影响

• 批准号: 0301815
• 负责人: Luis Vallejo
• 金额: --
• 依托单位: University of Pittsburgh
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0301815&HistoricalAwards=false
• 关键词: evolution; crushing; granular; materials; its

Granular materials forming part of the base of flexible pavements, rockfills, highway embankments, and foundations experience crushing as a result of static and dynamic loads. Very little is known about the effect that varying levels of crushing have on the engineering properties of granular materials (i.e. hydraulic conductivity, shear strength, and elastic moduli). Because of sustained crushing, the original engineering properties with which a structure (i.e. a pavement's granular base or a highway embankment) was designed will change during its engineering life. Changes in the original engineering properties could affect the stability of the structure and could make it unsafe. Thus, there is a need to understand the evolution and the mechanics of crushing in granular materials. To this effect we will: (1) conduct laboratory and simulation investigations on the evolution of crushing in granular materials. The laboratory investigation will involve tests that induce crushing in granular materials (static and dynamic compression and shear tests). The evolution of crushing in these tests will be evaluated by assessing the micro-structural changes that take place in the samples and by comparing the grain size distribution of the materials measured before and after the crushing tests. Also, the Discrete Element Method (DEM) will be used to study the level and distribution of the interparticle forces that cause crushing; and, (2) evaluate the changes in engineering properties caused by the crushing process. The engineering properties that will be evaluated before and after crushing are: hydraulic conductivity, shear strength, and the elastic moduli of the granular materials tested. The results of the research will be valuable to the geotechnical engineering community, for the better design of civil engineering structures such as flexible pavements and for a better understanding of the ways the stability and settlement experienced by highway embankments evolve as a result of crushing.

作为柔性路面、堆石体、高速公路路基和基础的一部分的颗粒材料由于静态和动态载荷而经历破碎。很少有人知道的效果，不同程度的破碎对粒状材料的工程性质（即水力传导性，剪切强度和弹性模量）。由于持续的破碎，结构（即路面的粒状基层或公路路堤）设计的原始工程性质将在其工程寿命期间发生变化。 原始工程性质的变化可能会影响结构的稳定性，并可能使其不安全。因此，有必要了解颗粒材料破碎的演变和机理。 为此，我们将：（1）进行实验室和模拟研究的颗粒材料破碎的演变。实验室调查将包括在粒状材料中诱导破碎的试验（静态和动态压缩和剪切试验）。通过评估样品中发生的微观结构变化，并通过比较破碎试验前后测量的材料粒度分布，对这些试验中的破碎演变进行评价。此外，离散单元法（DEM）将用于研究导致破碎的颗粒间力的水平和分布;（2）评估破碎过程引起的工程性质的变化。在破碎之前和之后将评估的工程性质是：水力传导性、剪切强度和测试的粒状材料的弹性模量。 研究的结果将是有价值的岩土工程界，更好地设计土木工程结构，如柔性路面和更好地了解的方式的稳定性和沉降经历的公路路基演变的结果粉碎。