Career: The Use of the Geotechnical Centrifuge for Physical Modelling of Geo-Environmental and Geotechnical Problems

Patricia J. Culligan MIT职业：使用土工离心机进行地质环境和土工问题的物理建模摘要本项目将使用土工离心机作为(a)研究含水层系统中有机污染物的行为和修复的研究工具，以及(b)将物理建模研究整合到土木和环境工程课程中的教育工具。岩土离心建模是一种实验方法，它允许在现实但控制良好的边界条件下对受重力影响的复杂问题进行小尺度物理建模。通过使用这种方法，土壤应力分布和重力（或浮力）驱动的流体位移都可以在实验室环境中以缩小的规模进行复制。除非进行全面的现场实验，否则不可能在离心力场之外正确地（可扩展地）复制这些效应。因此，土工离心机为许多地质环境和土工工程问题的物理建模提供了理想的工具。该项目的研究部分建议使用土工离心机来研究(i)不稳定非水相液体（NAPL）流动和土壤非均质性对NAPL通过渗透带运动的影响；（ii）在一系列流动条件下，饱和土壤中确定NAPL滞留的机制，以及（iii）影响最近两种NAPL修复技术（空气喷射和表面活性剂增强液压冲洗）性能的因素。该计划的结果将产生具有现场行为代表性的实验结果，可用于(i)量化含水层污染物负荷的时间和速率，例如，由于表面NAPL泄漏；（ii）提供在给定水力条件下的含水层内NAPL体积的估计；（iii）为两种新兴补救技术的部署制定定量指导方针。该研究的数据对于参数化、测试和验证概念传输模型和数值代码也将是非常宝贵的。该教育计划将使用土工离心机作为工具，将实践经验和基于问题的学习引入土木与环境工程（CEE）本科课程。教育计划的目标是：(i)开发一种方法，让中东欧学生看到他们的工程设计的效果，以及（ii）探索是否可以通过让学生接触物理建模和缩放原理来更好地教授工程力学的基础知识。该项目将利用麻省理工学院土木与环境工程系的土工离心机设备。该设施包括一个半径1.0米的平衡臂离心机，能够以400转/分钟的速度围绕中心轴旋转90公斤的土壤包，以及一个新的直径1.0米的迷你滚筒离心机，能够以1000转/分钟的速度围绕中心轴旋转1000公斤的土壤环。这两种离心机将用于这项工作的执行。

9875883 Patricia J. Culligan MIT CAREER: The use of the geotechnical centrifuge for physical modeling of geo-environmental and geotechnical problems Abstract This project will use the geotechnical centrifuge as (a) a research tool to investigate the behavior and remediation of organic contaminants in aquifer systems, and (b) an educational tool to integrate physical modeling studies into civil and environmental engineering curricula. Geotechnical centrifuge modeling is an experimental method that allows the small-scale physical modeling of complicated problems affected by gravitational forces under realistic, but well controlled, boundary conditions. By using this method, both soil stress distributions and gravity (or buoyancy)-driven fluid displacements can be replicated at a reduced scale in a laboratory environment. Correct (scaleable) replication of these effects is not possible outside a centrifugal field unless a full-scale field experiment is carried out. For this reason, the geotechnical centrifuge offers an ideal tool for the physical modeling of many geo-environmental and geotechnical engineering problems. The research component of this project proposes to use the geotechnical centrifuge to investigate (i) the effects of unstable nonaqueous phase liquid (NAPL) flow and soil heterogeneity on NAPL movement through the vadose zone; (ii) the mechanisms determining NAPL entrapment in saturated soils under a range of flow conditions, and (iii) factors affecting the performance of two recent NAPL remediation technologies, air sparging and surfactant-enhanced hydraulic flushing. The results of this program will produce experimental results representative of field behavior that can be used to (i) quantify the timing and rate of aquifer contaminant loading due, for example, to a surface NAPL spill; (ii) provide estimates of NAPL volume in aquifers under given hydraulic conditions; and (iii) develop quantitative guidelines for the deployment of two emerging remediation technologies. Data from the study will also be invaluable for the parameterization, testing and validation of conceptual transport models and numerical codes. The educational plan will use the geotechnical centrifuge as a vehicle for introducing hands-on-experience and problem based learning into the civil and environmental engineering (CEE) undergraduate curricula. The objectives of the educational plan are to (i) develop a means of allowing CEE students to see the effects of their engineering design, and (ii) to explore whether the fundamentals of engineering mechanics can be better taught by exposing students to principles of physical modeling and scaling. The project will make use of the geotechnical centrifuge facility in the Department of Civil and Environmental Engineering at MIT. This facility consists of a 1.0 m radius balanced arm centrifuge, which is capable of spinning a 90 kg package of soil around a central axis at 400 rpm, and a new 1.0 m diameter mini-drum centrifuge, which is capable of spinning a 1000 kg annulus of soil around a central axis at 1000 rpm. Both centrifuges will be used in the execution of this work.