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

天然土壤是由大小不一的颗粒组成的。从试验中观察到，颗粒分布一直被认为是影响土体强度的重要因素，从而影响土基基础设施的性能和稳定性。因此，了解颗粒分布对土体强度的影响是很重要的。然而，目前还没有一个分析模型能够明确地解释颗粒分布对土体强度的影响。该奖项支持基础性研究，以发展利用临界状态孔隙率的概念对考虑颗粒尺寸分布的土壤强度进行建模的基本知识。该方法对风化土中的滑坡、细粒冲刷引起的堤防失稳、颗粒破碎引起的坝体失稳、粉砂液化等岩土和地震工程问题具有一定的参考价值。这项研究的结果可用于降低未来因自然灾害而失败的风险，并开发更安全和更具弹性的设计方法。因此，这项研究的结果对美国经济和社会具有潜在的好处。这项研究的结果和活动被整合到土力学课程中，为工程教育和研究做出贡献。这项研究将解决颗粒分布对土壤强度的作用这一基本问题。本研究的主要目的是考虑不同大小颗粒的混合机理，建立临界状态下土壤的颗粒堆积理论。利用这一理论，可以建立一个分析模型，可以根据土体的颗粒分布来预测土体的临界状态孔隙比。为了促进理论的发展，将在不同类型的颗粒分布的土壤上进行一系列的试验。这项研究的学术价值有两个方面：(1)这项研究使我们能够使用颗粒堆积理论的新方法从基本的角度预测土壤强度，(2)这项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。这一奖项反映了NSF的法定使命，并通过使用基金会的智力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.