Collaborative Research: Improving the Sampling and Characterization of Intermediate Soils

中间土壤是由粉砂、粘土和沙子的不同混合物组成的，是常见的自然形成的沉积物，它可以为水坝、堤坝、高速公路、建筑和桥梁基础等基础设施项目带来设计挑战。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会产生特别大的问题。在某些情况下，中间土表现得像粘土，在另一些情况下表现得像砂土，这种不确定的过渡行为违反了用于粘土和砂土的成熟的知识基础和工程实践标准。中间土特性的不确定性迫使工程师在基础设施项目的设计中过于保守（即不经济），以确保社会的安全。该奖项支持的研究将开发通过钻孔和取样收集中间土壤样本的新方法，评估获得的土壤样本的质量，并在实验室中精确测量其工程特性，用于基础设施设计。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成果纳入课堂和专业短期课程，对学生和实践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对采样如何影响中间土壤的测量行为的理解。该范围包括模拟采样过程的高级三轴测试，各种采样器几何形状对样本状态影响的数值模拟，概念样本干扰框架的创建，以及在两个现场实施和验证研究结果。智力价值源于三个方面：(1)研究数据和发现将扩大我们对取样对中间土壤及其测量行为的影响的认识；(2)建立一个新的概念框架，跟踪样品扰动对中间土壤的影响，并创建相应的新样品质量“指数”参数；(3)通过现场测试开发和验证实践指南。该项目将为岩土工程界提供新的科学认识和实践指导。预计研究结果将适用于更广泛的材料，特别是粉煤灰、疏浚材料和矿山尾矿。

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.