Applying Insights from Biosilicification Processes to Ground Treatment: A Bio-Inspired Approach for Geoengineering

将生物硅化过程的见解应用于地基处理：地球工程的仿生方法

• 批准号: 0726488
• 负责人: Joseph Dove
• 金额: $ 29.13万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-01 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0726488&HistoricalAwards=false
• 关键词: Applying; Insights; Biosilicification; Processes; Ground

This research addresses a compelling opportunity in geoengineering to apply recent discoveries in the fundamental mechanisms controlling silica nucleation and growth in silicifying organisms. Biomimetic silicification (biosilicification) uses insights into biochemical pathways developed by these organisms to replicate, for a directed purpose, natural silicifying processes and products. This approach confers a number of advantages for ground treatment: 1) Potential for a new, sustainable means of creating cemented soil that can be tailored to specific geomechanical performance problems; 2) Uses readily?available, environmentally benign chemical materials; 3) Changes to soil and groundwater chemistry are not required and the process proceeds within the pH range of most natural soils; and, 4) Modifies the energy barriers to silica precipitation onto soil grain surfaces and may also improve the properties of the silica polymer that forms within the interstitial space. This approach has the distinct advantage of putting to work the biochemical machinery of organisms without the difficulties of culturing and maintaining active populations. Biosilicification has the potential for cost savings on ground improvement projects over traditional grouting methods because concentrations of silicic acid required could be much less. Cements formed by this process can potentially yield higher grouted soil strength and better long?term deformation behavior compared to traditional methods. Basic laboratory research will build on insights from preliminary studies to create cemented sand specimens using biosilicification. Materials will consist of Ottawa 20/30 sand, commercially available silicate solutions and amine?based, polyelectrolyte macromolecules. Compositions, concentrations and delivery methods of silicate and macromolecule solutions will be varied. Nondestructive in-situ microstructure characterization and distribution of cement in specimens will be made using x-ray tomography. Unconfined compression and drained triaxial compression tests will be used to assess strength gain with time; stress-strain, stiffness and strength behavior; and, long-term, constant load strength. The potential for biomimetic healing of broken cement bonds will be evaluated. Silicification experiments will be conducted to determine cement strength and the strength of cement to grain bonds. Vickers hardness and elastic modulus of the cement will be determined by nano?indentation tests. Comparisons will be made with traditional silicate?grouted sand specimens. Through the unique combination of the geoengineering and biogeochemistry expertise of the PIs, this project is an opportunity for innovative, and possibly transformative, advances with broad societal, economic and educational impacts. Societal benefits are derived from a ground improvement method that could lower the cost of infrastructure, using materials that are non?toxic to humans and ecosystems, and prevent worker exposure to chemical hazards. Considering the potential for commercial application of this new process, impacts to the geotechnical profession are possibly large. Interactions with practitioners during the project will be an especially fruitful avenue for transferring the discoveries to practice. Undergraduate students will be encouraged to work on this exciting interdisciplinary research project. Graduate students on the project will have the opportunity to develop expertise in the growing area of applied biogeochemistry. As such, they will have frontline experience in transforming rapidly advancing scientific discoveries from the bench top to the geoengineering scale. In conjunction with the Center for Enhancement of Engineering Diversity, academically qualified women, minorities and first generation university students will be recruited. Women students will especially benefit from mentoring by co-PI P.Dove and from the scholarship opportunities available through the NSF sponsored AdvanceVT program.

这项研究解决了地球工程学中一个引人注目的机会，应用了控制硅化有机体中二氧化硅成核和生长的基本机制中的最新发现。仿生硅化(生物硅化)利用对这些有机体开发的生化途径的洞察，为定向目的复制自然硅化过程和产品。这种方法为地基处理提供了许多优势：1)有可能产生一种新的、可持续的方法来创造可根据特定地质力学性能问题量身定做的水泥土；2)使用容易获得的、对环境无害的化学材料；3)不需要改变土壤和地下水的化学成分，这一过程在大多数天然土壤的pH范围内进行；以及4)改变土壤颗粒表面二氧化硅沉淀的能量屏障，还可以改善间隙空间内形成的二氧化硅聚合物的性质。这种方法具有明显的优势，可以使生物体的生化机制发挥作用，而不会遇到培养和维持活跃种群的困难。与传统的灌浆方法相比，生物硅化在地基改善项目中具有节省成本的潜力，因为所需的硅酸浓度可能要低得多。与传统方法相比，这种方法形成的水泥可以产生更高的灌浆土强度和更好的长期变形行为。基础实验室研究将建立在初步研究的基础上，利用生物硅化作用创建胶结砂样。材料将由渥太华20/30沙子、商用硅酸盐溶液和胺基聚电解质大分子组成。硅酸盐和高分子溶液的组成、浓度和输送方式将有所不同。利用X射线层析成像技术对试件中水泥的非破坏性原位微结构表征和分布进行研究。无侧限压缩和排水三轴压缩试验将用于评估强度随时间的增加；应力-应变、刚度和强度行为；以及长期恒定载荷强度。将评估断裂的水泥粘合的仿生愈合的潜力。将进行硅化实验，以确定水泥强度和水泥与颗粒的粘结强度。水泥的维氏硬度和弹性模数将通过纳米压痕测试来确定。将与传统的硅酸盐灌浆砂样进行比较。通过将地球工程和生物地球化学专业知识独特地结合在一起，这一项目为创新和可能具有变革性的进步提供了机会，并产生了广泛的社会、经济和教育影响。社会效益来自一种土地改良方法，这种方法可以降低基础设施的成本，使用对人类和生态系统无毒的材料，并防止工人暴露在化学危险中。考虑到这一新工艺的商业应用潜力，对岩土专业的影响可能很大。在项目期间与实践者的互动将是将发现转化为实践的特别富有成效的途径。本科生将被鼓励参与这一令人兴奋的跨学科研究项目。该项目的研究生将有机会在不断增长的应用生物地球化学领域发展专业知识。因此，他们将拥有将快速推进的科学发现从工作台转化为地球工程规模的第一线经验。与加强工程多样性中心合作，将招募学术合格的妇女、少数民族和第一代大学生。女学生将特别受益于共同派P.Dave的指导，以及通过NSF赞助的AdvanceVT计划提供的奖学金机会。