Deformation and Failure Behavior of Soils under Erosion

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。土壤侵蚀是大坝和防洪堤失灵的主要原因，并可能造成灾难性后果，例如2006年新奥尔良和2008年爱荷华州的灾难。根据最新的美国成绩单？美国土木工程师协会2009年发布的《基础设施》报告中，大坝和防洪堤的评级为D -。许多水坝和防洪堤在结构上存在缺陷，几乎不可能坍塌。土结构内部侵蚀的风险成为一个关键问题。本研究的主要目的是解决由内部侵蚀引起的变形和不稳定的机制。将建立一个应力-应变模型，该模型将(1)考虑孔隙崩塌的微观尺度机制，(2)考虑比体积和级配等内部结构的演变。将该应力应变规律应用于分析侵蚀作用下土结构的有限元方法中。这项研究工作将与南特中央学院合作进行，目前南特中央学院正在进行一项实验性土壤侵蚀研究计划。合作者将为这项研究提供必要的实验结果。本研究具有双重科学意义：(1)该研究将引领损伤力学的新方向，即损伤不是由外载荷引起的，而是由部分材料成分的损失引起的。(2)微观力学建模方法，其中的行为是从假设的机制推导出来的，将提供对潜在物理过程的洞察。该研究还将把土体结构的数学表达式（如孔隙和粒径分布）引入到本构模型的物理学中，这对于建立土壤本构理论具有核心意义。更广泛的影响将如下：(1)通过将研究成果和活动纳入焦强度和土力学研究生课程，将研究与教育结合起来。(2)通过让马萨诸塞大学东北联盟项目的本科生参与进来，扩大参与范围，提高多样性。该项目是美国国家科学基金会资助的一个项目，旨在招收代表性不足的少数民族学生进入科学和工程专业攻读博士学位。(3)通过与南特圣纳泽尔土木工程实验室建立国际合作，加强研究和教育基础设施。(4)加强土木工程基础设施建设，加强对山体滑坡、洪水等自然灾害的防御。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Soil erosion is the main cause of failure for dams and levees and can have disastrous consequences, such as the catastrophies in New Orleans in 2006 and in Iowa in 2008. According to the latest Report Card for America?s Infrastructure, issued in 2009 by the American Society of Civil Engineers, dams and levees are in the D minus range. Many dams and levees are structurally deficient and barely above failing. The risk of internal erosion in earth structures becomes a critical issue. The main goal of this research is to address the mechanics of deformation and instability caused by internal erosion. A stress-strain model will be developed that will (1) consider the micro-scale mechanism of pore collapse, and (2) account for the evolution of internal structure such as specific volume and gradation. T his stress strain law will be implemented into a finite element method capable of analyzing earth structure under erosion. This research work will be conducted in collaboration with Ecole Centrale de Nantes, where an experimental soil erosion research program is currently in progress. The collaborator will provide experimental results necessary for this research.The scientific significance of this research is twofold: (1) The investigation will lead to a new direction of damage mechanics, in which the damage is not caused by external load, but rather by a loss of part of the material constituents. (2) The micromechanics modeling method, in which the behavior is derived from postulated mechanisms, will provide insight into the underlying physical processes. The study will also bring the mathematical expressions of soil fabric (such as voids and particle size distribution) into the physics of constitutive models, which is of core importance to a constitutive theory for soil.The broader impacts will be as follows: (1) Integrate research and education by incorporating the research results and activities into graduate courses on sear strength and soil mechanics. (2) Broaden participation and enhance diversity by involving undergraduate students from the Northeast Alliance Program at the University of Massachusetts, an NSF funded program aimed at recruiting underrepresented minority students into doctoral study in science and engineering. (3) Enhance infrastructure for research and education by establishing international collaboration with the Civil Engineering Laboratory of Nantes.Saint-Nazaire. (4) Develop a defense against natural disasters such as landslides and floods through the enhancement of civil engineering infrastructure.