CAREER: Fines Induced Liquefaction in Alluvial Sands and Geotechnical Engineering Education

9701467 Yamamuro这一行动是为了支持根据国家科学基金会教师早期职业发展(Career)计划提交的综合研究和教育增强项目。大多数关于土壤液化的研究都是在干净的沙子上进行的，而大多数有记录的地震引起的液化历史案例都发生在冲积粉砂上。目前关于细小颗粒(小于0.074 mm)对土壤液化行为的影响的观点是，它要么抑制液化，要么影响甚微。然而，这并不一定是正确的。粉砂的行为也被观察到非常不寻常。研究计划的四个主要任务和目标是：(1)通过单调和循环加载进行排水和不排水试验，研究粉砂的非常规特性。目的是探索观察到的非常规行为的界限。(2)采用扫描电子显微镜和薄片分析方法，对不同沉积方法所形成的粉砂土组构进行了评价。在此之后，将研究在一个圆柱形垂直沉淀室中由水沉积过程产生的土壤组构。这样做的目的是确保冲积沉积产生的织物准确地结合到测试样品中。然后，将使用离散元方法(DEM)对土壤结构进行建模，目的是验证在冲积沉积过程中在粉砂中创建的“亚稳定”结构可能的“坍塌”机制。(3)在粉砂上制作的双壁定标室中进行模型锥贯入仪试验(CPT)。目的是评价现有的现场液化评价方法和颗粒大小的影响。(4)对弹塑性非关联流动本构模型进行修正，使之更好地反映土体的非常规性态。其目的是能够预测冲积粉砂中的液化。三个主要的教育目标是：(L)提高学生在充当仅通过网络技术连接的独立的项目团队成员时的电子通信技能。(2)通过制作互动视频，为本科生提供更多接触先进土力学试验的机会，以改善本科土力学教育。将为单调和循环三轴试验、扭转剪切、CPT和压力计等试验制作视频。这将补充基本的本科生实验室经验。(3)鼓励少数族裔参与克拉克森大学的岩土工程专业。要做到这一点，最好的办法是参加麦克奈尔计划，该计划资助合格的少数族裔学生在暑期参加本科生研究。

9701467 Yamamuro This action is to support an integrated research and educational-enhancement project submitted under the NSF Faculty Early Career Development (CAREER) Program. Most research into liquefaction of soils has been performed on clean sands, while most of the documented historic cases of earthquake-induced liquefaction have occurred in alluvial silty sands. The current view of the effect of fines (particles smaller than 0.074 mm) on the liquefaction behavior of soils is that it either inhibits liquefaction or that it has little effect. However this is not necessarily correct. The behavior of silty sands has also been observed to be highly unconventional. The four major tasks and objectives of the research program are: (1) To investigate the unconventional behavior of silty sands by performing drained and undrained testing using monotonic and cyclic loading. The objective is to explore the bounds of the observed unconventional behavior. (2) To evaluate, using scanning electron microscope and thin- sections analysis, the soil fabric of silty sands formed by the different depositional methods used to create test specimens. This will be followed by a study of soil fabric created by water depositional processes in a fabricated cylindrical vertical sedimentation chamber. The objective is to ensure that the fabric created by alluvial deposition is incorporated accurately into test specimens. The soil fabric will then be modeled using Discrete Element Methods (DEM), the objective being to verify possible 'collapse' mechanisms of 'meta-stable' structures created in silty sands during alluvial deposition. (3) To perform model cone penetrometer tests (CPT) in a fabricated double-walled calibration chamber on silty sands. The objective is to evaluate existing insitu liquefaction assessment methods and the effect of grain size. (4) To modify an elasto-plastic, non-associated flow constitutive soil model to capture the unconventional behavior pattern. The objective is to enable predictions of liquefaction in alluvial silty sand. The three main educational objectives are: (l) To improve students' electronic communications skills when acting as 'disassociated' project team members connected only by networking technology. (2) To improve undergraduate soil mechanics education by providing undergraduate students with greater exposure to advanced soil mechanics testing by developing interactive videos. Videos will be developed for tests such as monotonic and cyclic triaxial testing, torsion shear, CPT, and pressuremeter. This will supplement the basic undergraduate laboratory experience. (3) To encourage minority participation into the geotechnical engineering program at Clarkson University. This will be best accomplished by participation in the McNair Program which funds qualified minority students to participate in undergraduate research during summers.