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

9875883帕特里夏·J·卡利根麻省理工学院的职业生涯：使用土工离心机对地质环境和土工问题进行物理模拟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补救的研究工具，以及(B)将物理模型研究整合到土木工程和环境工程课程中的教育工具。土工离心机模拟是一种实验方法，它允许在真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规模物理模拟。通过使用这种方法，可以在实验室环境中以较小的规模复制土壤应力分布和重力(或浮力)驱动的流体位移。除非进行全面的现场实验，否则在离心场之外不可能正确地(可缩放地)复制这些效应。因此，土工离心机为许多岩土环境和岩土工程问题的物理模拟提供了理想的工具。本项目的研究部分建议使用土工离心机来研究(I)不稳定的非水相液体(NAPL)流动和土壤非均质性对NAPL在包气带中移动的影响；(Ii)在各种流动条件下决定NAPL在饱和土壤中被困的机制，以及(Iii)影响最近两种NAPL修复技术性能的因素，这两种修复技术是空气喷雾和表面活性剂强化水力冲洗。该方案的结果将产生代表实地行为的实验结果，可用于(I)量化含水层污染物负荷的时间和速率，例如由于地表NAPL泄漏；(Ii)提供特定水力条件下含水层NAPL体积的估计；以及(Iii)为部署两种新兴补救技术制定量化指导方针。这项研究的数据对于概念性运输模型和数值代码的参数化、测试和验证也将是非常宝贵的。该教育计划将使用土工离心机作为一种工具，将实践经验和以问题为基础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基础知识。该项目将利用麻省理工学院土木工程和环境工程系的土工离心机设施。该设施包括一台半径为1.0米的平衡臂离心机，它能够以每分钟400转的速度旋转90公斤重的土壤，以及一台新的1.0米直径的迷你滚筒离心机，它能够以每分钟1000转的速度旋转一圈1000公斤的土壤。这两台离心机都将用于执行这项工作。

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.