Collaborative Research: Improving the Sampling and Characterization of Intermediate Soils

中间土由粉土、粘土和砂的不同混合物组成，是常见的天然沉积物，可能会给基础设施项目（包括水坝、堤坝、公路以及建筑和桥梁基础）带来设计挑战。岩土工程实践能够很好地表征粘土和砂，但这两种材料与淤泥的混合物可能特别成问题。在某些情况下，中间土的行为像粘土，而在其他情况下，行为像砂，这种不确定的过渡行为违反了用于粘土和砂的成熟的知识基础和工程实践标准。中间土壤特性的不确定性迫使工程师过于保守（即，不经济），以确保社会安全的基础设施项目的设计。该奖项支持的研究将开发新的方法，用于通过钻孔和取样收集中间土壤样品，评估所获得的土壤样品的质量，并在实验室中准确测量其工程特性，用于基础设施的设计。研究结果将为工程专业提供实用指导，从而使在中间土壤上建造的基础设施设计更加可靠和经济。该项目还将通过将项目研究结果纳入课堂和专业短期课程，对学生和执业工程师进行教育和培训，从而促进劳动力发展。这个合作研究项目的主要目标是提高采样如何影响测量的中间土壤的行为的理解。范围涉及先进的三轴测试，将模拟采样过程，各种采样器几何形状对样品状态的影响的数值建模，概念性样品扰动框架的创建，以及在两个现场的研究结果的实施和验证。其学术价值来自三个方面：（1）研究数据和发现，将扩大我们对采样对中间土壤及其测量行为的影响的认识;（2）制定一个新的概念框架，跟踪样本扰动对中间土壤的影响，并创建相应的新样本质量“指数”参数;以及（3）通过实践指南的现场测试来开发和验证。该项目将提供岩土工程界迫切需要的新的科学认识和实践指导。预计研究结果还将适用于更广泛的材料，特别是粉煤灰、疏浚材料和尾矿。

Intermediate soils, which consist of varying mixtures of silts, clays, and sands, are common, naturally occurring deposits that can create design challenges for infrastructure projects involving dams, levees, highways, and building and bridge foundations. Geotechnical engineering practice is able to characterize clays and sands well, but it is the mixture of these two materials in combination with silt that can be particularly problematic. In some cases intermediate soils behave like clays and in others the behavior is like sands, and this uncertain transitional behavior violates the well-established knowledge base and standard of engineering practice used for clays and sands. The uncertainty in the characterization of intermediate soils forces engineers to be overly conservative (i.e., uneconomical) in the design of infrastructure projects to ensure the safety of society. This award supports research that will develop new methodologies for collecting intermediate soil samples by drilling and sampling, evaluating the quality of soil samples obtained, and accurately measuring their engineering properties in the laboratory for design of infrastructure. Outcomes from the research will provide practical guidance to the engineering profession leading to more reliable and economical design of infrastructure built upon intermediate soils. The project will also result in workforce development through the education and training of students and practicing engineers by incorporation of project findings into the classroom and professional short courses. The primary objective of this collaborative research project is to improve the understanding of how sampling influences the measured behavior of intermediate soils. The scope involves advanced triaxial testing that will simulate the sampling process, numerical modeling of the influence of various sampler geometries on sample state, creation of a conceptual sample disturbance framework, and implementation and validation of research findings at two field sites. The intellectual merit originates from three aspects: (1) research data and findings that will expand our knowledge of the effects of sampling on intermediate soils and their measured behavior; (2) formulation of a new conceptual framework that tracks the effect of sample disturbance on intermediate soils and creation of a corresponding new sample quality "index" parameter; and (3) development and validation via field testing of practice guidelines. The project will provide new scientific understanding and practical guidance that is urgently needed by the geotechnical engineering community. It is also anticipated that the research findings will be applicable to a broader range of materials, most notably fly ash, dredge materials, and mine tailings.