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

这项行动是为了支持一项综合研究和教育增强项目，该项目是在美国国家科学基金会教师早期职业发展（Career）计划下提交的。大多数关于土壤液化的研究都是在干净的沙子上进行的，而大多数记录在案的地震液化的历史案例都发生在冲积粉质沙子上。目前关于细粒（小于0.074 mm的颗粒）对土壤液化行为的影响的观点是，它要么抑制液化，要么几乎没有影响。然而，这并不一定正确。粉质砂的性质也被认为是高度非常规的。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，研究粉质砂的非常规行为。目的是探索观察到的非常规行为的界限。(2)利用扫描电子显微镜和薄片分析，评价不同沉积方法形成的粉质砂的土壤结构，并制作试样。随后将在一个制造的圆柱形垂直沉降室中研究由水沉积过程产生的土壤结构。目的是确保冲积物沉积形成的织物被准确地纳入测试样本。然后将使用离散元方法（DEM）对土壤结构进行建模，目的是验证冲积沉积期间粉质砂中形成的“亚稳定”结构的可能“崩溃”机制。(3)在粉质砂土上的自制双壁标定室中进行模型锥贯仪试验。目的是评价现有的原位液化评价方法和颗粒尺寸的影响。(4)修改弹塑性、非关联流动本构土模型，以捕捉非常规行为模式。目的是预测冲积粉质砂的液化。三个主要的教育目标是：(1)提高学生在作为只通过网络技术连接的“分离”项目小组成员时的电子通信技能。(2)改进本科土力学教育，通过制作互动视频，让本科生更多地了解先进的土力学测试。将为单调和循环三轴试验、扭剪、CPT和压力计等试验开发视频。这将补充基本的本科实验室经验。(3)鼓励少数民族参与克拉克森大学的岩土工程项目。这将通过参加麦克奈尔项目来实现，该项目资助合格的少数民族学生在夏季参加本科研究。

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.