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。 试验表明，颗粒级配是影响土体强度的重要因素，进而影响地基基础设施的使用性能和稳定性。因此，了解颗粒尺寸分布对土壤强度的影响是很重要的。 然而，目前还没有一个分析模型，可以明确地说明颗粒尺寸分布对土强度的影响。 该奖项支持基础研究，以开发考虑颗粒尺寸分布的土壤强度建模的基本知识，使用临界状态孔隙比的概念。本研究所提出的方法，对于风化土中的滑坡、细颗粒侵蚀引起的堤坝破坏、颗粒破碎引起的堤坝失稳、粉砂液化等岩土工程和地震工程问题，具有一定的参考价值。这项研究的结果可用于减少未来因自然灾害而发生故障的风险，并开发更安全，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。本研究将解决颗粒尺寸分布在土强度中的作用这一基本问题。本研究的主要目的是建立一个考虑不同粒径颗粒混合机理的临界状态下的颗粒堆积理论。 通过使用这一理论，将开发一个分析模型，可以预测的临界状态孔隙比的土壤颗粒尺寸分布的基础上。 为了促进理论的发展，一系列的实验测试将进行各种类型的粒度分布的土壤。 这项研究的学术价值是双重的：（1）本研究利用颗粒堆积理论的新方法，从基本的角度预测土的强度，（2）本次调查推进了知识-该奖项反映了NSF的法定使命，并被认为是值得支持的，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。

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.