Analytical Modeling for the Effect of Grain Size Distribution on the Critical State of Granular Soil

天然土壤是由各种大小的颗粒组成的。从试验中观察到，粒径分布一直被认为是影响土壤强度的一个重要因素，从而影响到建立在土壤上的基础设施的性能和稳定性。因此，了解粒径分布对土体强度的影响是十分重要的。然而，目前还没有一个解析模型可以明确地解释粒度分布对土强度的影响。该奖项支持基础研究，以开发基本知识，模拟土壤的强度，考虑到使用临界状态空隙比的概念的粒度分布。本研究开发的方法将有助于解决岩土工程和地震工程问题，如风化土中的滑坡、细颗粒侵蚀引起的堤坝破坏、颗粒破碎引起的大坝失稳以及粉砂液化。这项研究的结果可以用来减少未来因自然灾害而失败的风险，并开发更安全、更有弹性的设计方法。因此，这项研究的结果对美国经济和社会有潜在的好处。本研究的结果和活动被整合到土力学课程中，有助于工程教育和研究。本研究将解决粒径分布在土强度中的作用这一基本问题。本研究的主要目标是建立临界状态下土体的颗粒堆积理论，考虑不同粒径颗粒的混合机制。通过使用这一理论，将建立一个分析模型，可以根据其粒度分布预测土壤的临界状态空隙比。为了促进理论的发展，我们将对不同粒度分布类型的土壤进行一系列的实验试验。本研究的智力价值在于：(1)本研究使我们能够利用颗粒堆积理论的新方法从基础角度预测土的强度；(2)本研究通过提供一种分析颗粒聚集行为的方法，推动了连续介质力学的知识边界。该奖项反映了美国国家科学基金会的法定使命，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。

Natural soil is composed of particles of various sizes. Observed from experiments, particle size distribution has long been recognized as an important factor that influences the strength of soil, and consequently influences the performance and stability of infrastructures founded on soil. Therefore, it is important to understand how the soil strength is influenced by the particle size distribution. However, currently there is no analytical model that can explicitly account for the effect of particle size distribution on soil strength. This award supports fundamental research to develop the essential knowledge for modeling the strength of soil with consideration of particle size distribution using the concept of critical state void ratio. The method developed from this research will be useful for geotechnical and earthquake engineering problems, such as landslides in weathered soil, levee failure due to erosion of fine particles, dam instability due to grain crushing, and liquefaction of silty sand. Results of this research can be used to reduce future risks of failures due to natural disasters, and to develop design methodologies which are safer and more resilient. Thus, results from this research have potential benefits to the U.S. economy and society. The results and activities of this research are integrated into courses on soil mechanics contributing to engineering education and researchThis research will address the fundamental issue on the role of particle size distribution in soil strength. The main goal of this research is to develop a particle packing theory for soils at critical state, considering the mix mechanism of particles of various sizes. Through the use of this theory, an analytical model will be developed that can predict the critical state void ratio of soil based on its particle size distribution. To facilitate the theoretical development, a series of experimental tests will be performed on soils with various types of grain size distribution. The intellectual merit of this research is twofold: (1) This investigation allows us to predict the soil strength from a fundamental perspective by using a novel approach of particle packing theory, (2) This investigation pushes forward the knowledge-boundary of continuum mechanics by providing a methodology for analyzing the behavior of particle assembly.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.