RAPID: Biostimulation for Biocementation at Field Scale Treatment Depths

RAPID：用于现场规模处理深度生物水泥的生物刺激

• 批准号: 1539774
• 负责人: Jason DeJong
• 金额: $ 4.28万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1539774&HistoricalAwards=false
• 关键词: RAPID; Biostimulation; Biocementation; Field; Scale

Soil improvement is often required when the soil supporting the foundations for structures, or soil used for embankments, and other earthworks lack sufficient strength and stiffness to perform satisfactorily. Current engineering practice relies primarily on the use of chemical grouts and mechanical methods to improve soils, despite environmental concerns regarding high embodied energies and documented groundwater contamination incidents. Microbially Induced Calcite Precipitation (MICP) offers an environmentally conscious bio-mediated soil improvement alternative that can improve a soil's engineering properties through the precipitation of calcite at soil particle contacts (biocementation). Although researchers have extensively demonstrated the ability of MICP to improve soils, the need for cultivation and injection of specialized non-native bacterial strains has restricted the technology from becoming a cost-competitive and environmentally permissible soil improvement technique. This award supports research critical to the advancement of the technology, by assessing the feasibility of using native bacteria to complete the process at depths relevant to practical engineering application. Stimulation of native bacteria will eliminate cultivation costs and potential long-term environmental and ecological impacts by forgoing the introduction of non-native bacteria into native soil ecosystems. This advancement would provide industry with financial and environmental incentives for adoption of the method into practice and therefore attain important societal and environmental benefits. This research will involve interdisciplinary expertise in microbiology, geotechnical engineering, and geology by engaging an international collaboration of researchers. The feasibility of stimulating native bacteria at depths typically required for mitigation of geotechnical hazards such as liquefaction is unknown. This research will provide important and unprecedented insight about the distributions, relative abundances, and feasibility of stimulating native bacteria in natural soil deposits to complete biocementation with depth. Previous experiments have successfully demonstrated the ability of stimulated native bacteria to enable biocementation, but these studies have only involved surficial soils. Total concentrations of native soil microorganisms are expected to decrease with depth however, due to reductions in total soil organic matter and oxygen availability. In this study, a drilling and sampling program will be conducted to obtain samples from discrete depths up to 15 meters within a natural soil deposit for microbiological characterization and geotechnical testing. Batch experiments will be performed on obtained samples to optimize stimulation treatments using microbiological analyses and timed measurements of process biogeochemistry. Column experiments will be also performed to evaluate the effectiveness of stimulation techniques to enrich for native bacterial populations and improve soil geotechnical properties with depth through microbiological, biogeochemical, and geotechnical monitoring.

当支撑结构基础的土壤或用于加固的土壤以及其他土方工程缺乏足够的强度和刚度时，通常需要进行土壤改良。 目前的工程实践主要依赖于使用化学灌浆和机械方法来改善土壤，尽管环境问题，高体现能源和记录的地下水污染事件。 微生物诱导的方解石沉淀（MICP）提供了一种具有环保意识的生物介导的土壤改良替代方案，可以通过方解石在土壤颗粒接触处的沉淀（生物胶结）来改善土壤的工程性质。 尽管研究人员已经广泛证明了MICP改善土壤的能力，但需要培养和注射专门的非天然细菌菌株，这限制了该技术成为一种具有成本竞争力和环境允许的土壤改良技术。 该奖项通过评估使用天然细菌在与实际工程应用相关的深度完成工艺的可行性，支持对技术进步至关重要的研究。 通过放弃将非本地细菌引入本地土壤生态系统，刺激本地细菌将消除培养成本和潜在的长期环境和生态影响。 这一进步将为工业界提供财政和环境激励措施，鼓励其将该方法付诸实践，从而实现重要的社会和环境效益。这项研究将涉及微生物学，岩土工程和地质学的跨学科专业知识，通过国际研究人员的合作。在减轻岩土工程危害（如液化）通常所需的深度刺激天然细菌的可行性尚不清楚。 这项研究将提供重要的和前所未有的洞察力的分布，相对丰度，以及刺激天然土壤沉积物中的原生细菌，以完成生物胶结与深度的可行性。以前的实验已经成功地证明了刺激的本地细菌，使生物胶结的能力，但这些研究只涉及表层土壤。 然而，由于土壤总有机质和氧气供应量的减少，预计原生土壤微生物的总浓度将随着深度的增加而减少。 在本研究中，将进行钻孔和取样程序，以从天然土壤存款内最多15米的离散深度获取样本，用于微生物表征和岩土工程测试。 将对获得的样品进行批实验，以使用微生物分析和过程生物化学的定时测量来优化增产处理。 还将进行柱实验，以评估增产技术的有效性，从而通过微生物、土壤地球化学和岩土工程监测，丰富原生细菌种群并改善土壤岩土工程性质。