An Experimental Study of Biopolymer Reduction of Cohesionless Soil Permeability for Landfill Cover Applications

这一职业生涯倡议的总体目标是调查机制的替代，蒸发蒸腾覆盖系统的废物遏制应用的性能，而在同一时间，开发替代的教育模块，将广泛的人群（前，后，和大学生）的环境岩土工程的挑战。预计这一综合研究和教育举措将通过以下方面的进展作出重大贡献：（1）对复杂的非饱和流动过程的基本了解，（2）离心分离和数值模拟相结合，（3）干旱和半干旱环境中废物覆盖系统的设计，（4）将研究纳入工程教育，（5）设计和环境岩土工程的教学，和（6）少数民族高中生和专业的外展策略。即使现场监测程序和数值模拟提供了宝贵的洞察土被系统的行为，验证预测数值工具的重要任务仍然是，充其量，不完整的。这里的研究计划，然后使用离心模型作为岩土工程数据的额外来源，以获得进一步了解复杂的非饱和过程中发生的蒸散覆盖。该模型将允许系统地控制相关变量，结合设计的关键天气和土壤条件，并显着减少所需的时间来获取实验数据。与此相关的主要事实是，离心机模型将使用来自美国两个最重要的危险废物场地（加州的OII超级基金填埋场和科罗拉多的落基山兵工厂）的实际土壤，而不是一般的土壤。这两个地点目前分别正在实施和寻求实施蒸散覆盖系统。而不是试图复制实际的原型盖在离心机中，这项研究追求验证和校准的分析工具中使用的封面分析。因此，全面的不饱和流数值模拟的离心实验将进行，然后由一个仔细的参数评估的通用原型盖。这项调查将利用PI过去的经验，作为离心模型和设计师和数值模拟的蒸散覆盖在OII超级基金网站。一些主要的问题要调查，通过结合离心和数值模拟包括适当的表面通量边界条件的代表性，覆盖行为的敏感性滞后土壤水力特性，并在数值模拟中的下边界条件的适当选择。作为教育计划的一部分，将制定两个教育单元，这两个单元与研究计划密切相关，并从研究计划中汲取主要力量。同样的两个模块将用于实现与不同人群相关的四个具体工程教育目标。这项工作将试图“把网站的校园”，开发：（一）多媒体案例历史系列，和（二）现场替代封面演示。这些教育模块将用于满足以下需求：（1）增强土木工程本科生的设计经验，（2）研究生的环境岩土工程课程开发，（3）有效招募代表性不足的少数民族高中学生进入工程项目，以及（4）积极推广到专业社区，包括本地和国际。通过实施替代方案，虽然仍然结构化的方案，教育计划不仅将促进目前的进展，在地质环境工程，但它也将解决工程教育的一般缺陷。

The overall objective of this CAREER initiative is to investigate the mechanisms governing the performance of alternative, evapotranspirative cover systems for waste containment applications while, at the same time, to develop alternative educational modules that will expose a wide range of populations (pre-, post-, and college students) to the challenges of environmental geotechnics. It is expected that this integrated research and education initiative will provide significant contributions through advancements in: (1) basic understanding of complex unsaturated flow processes, (2) combined centrifuge and numerical modeling, (3) design of waste cover systems in arid and semi-arid environments, (4) integration of research into engineering education, (5) teaching of design and of environmental geotechnics, and (6) outreaching strategies for minority high school students and the profession.Even though field monitoring programs and numerical simulations have provided invaluable insight into the behavior of earthen cover systems, the important task of validating predictive numerical tools remains, at best, incomplete. The research plan herein is then to use centrifuge modeling as an additional source of geotechnical data in order to gain further understanding into the complex unsaturated processes that take place in evapotranspirative covers. Centrifuge modeling will allow systematic control of the relevant variables, combination of weather and soil conditions critical for design, and significant reduction in the time needed for acquisition of experimental data. Of major relevance is the fact that, instead of generic soils, actual soils from two of the nation's most significant hazardous waste sites (California's OII Superfund Landfill and Colorado's Rocky Mountain Arsenal) will be used in the centrifuge models. These two sites are, respectively, currently implementing and seeking implementation of evapotranspirative cover systems. Rather than attempting to replicate actual prototype covers in the centrifuge, this research pursues validation and calibration of analytical tools used in cover analysis. Consequently, comprehensive unsaturated flow numerical simulations of the centrifuge experiments will be undertaken, followed by a careful parametric evaluation of generic prototype covers. This investigation will capitalize on the PI's past experience as centrifuge modeler and as designer and numerical modeler of the evapotranspirative cover at the OII Superfund site. Some of the major issues to be investigated through combined centrifuge and numerical modeling include the proper representation of surface flux boundary conditions, the sensitivity of the cover behavior to hysteresis in soil hydraulic properties, and the appropriate selection of the lower boundary condition in numerical simulations. Two educational modules, which are significantly related to and draw major strength from the research plan, will be developed as part of the education plan. The very same two modules will be used to achieve four specific engineering educational goals relevant to different populations. This effort will attempt to "bring the site to the campus" by developing: (i) a Multimedia Case History Series, and (ii) a Field Alternative Cover Demonstration. These educational modules will be used to address the needs for: (1) enhanced design experience for civil engineering undergraduate students, (2) curriculum development in environmental geotechnics for graduate students, (3) effective recruitment of underrepresented minority high school students into engineering programs, and (4) active outreach to the professional community, both locally and internationally. Through implementation of alternative, though still structured programs, the education plan will not only promote current advances in geoenvironmental engineering, but it will also address general deficiencies in engineering education.