Bio-Cementation Field-Scale Trials: Addressing the Challenges of Treatment Uniformity & Verification, Biostimulation, & By Product Management

生物水泥现场规模试验：应对处理均匀性的挑战

• 批准号: 1234367
• 负责人: Jason DeJong
• 金额: $ 59.66万
• 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: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1234367&HistoricalAwards=false
• 关键词: Bio; Cementation; Field; Scale; Trials

Bio-mediated soil improvement, and in particular the use of microbially induced calcite precipitation (MICP) as a natural bio-mediated cementation process for sand improvement, has progressed rapidly. We propose to directly address the critical issues of treatment uniformity & verification, bio-stimulation, and by-product management through modest field-scale trials that are supported by experimental and numerical modeling techniques. Specifically, we proposed to perform two field-scale trials in a deep test chamber using natural liquefiable sand. The first trial relies on bio-augmentation (injection of bacteria) in order to provide a low-risk ground-truth set of data unencumbered by the unknown spatial distribution of native bacteria that we face with bio-stimulation. This first experiment builds directly on extensive laboratory research, has high likelihood of success and thus will enable focus on treatment uniformity and verification using in-situ and laboratory geotechnical tests. The second trial will use bio-stimulation (activation of native sessile bacteria) that introduces the additional degree of freedom (spatial distribution of bacteria) but is also the most desirable field scale treatment approach for the future. It is more practical (cost, permitting), has reduced by-product generation, and may increase uniformity. Both trials will enable study of by-product generation during treatment and its fate after soil improvement. We believe that field-scale treatment in a large test chamber provides the necessary balance between length scale and experimental control to rigorously, but practically, address these issues. The full-scale work will be supported by parallel efforts developing a robust bio-stimulation technique and modeling of the field trials to develop a predictive modeling tool that accounts for bio-stimulation, by-product transport and fate, and spatial heterogeneity. The scope builds on the team?s continued research activities over the past eight years, making this a challenging, yet feasible, scope. We envision that successful completion of this project will be transformative through improvement in treatment uniformity, validation of verification tests, development of a bio-stimulation approach, and management by-product generation and fate. Bio-mediated soil improvement is a relatively new, novel technique for improving the engineering properties of soils to a level where civil infrastructure can be supported. In particular, microbially induced calcite precipitation, or MICP, is a process in which microbial activity in the soil temporarily modifies local environmental conditions such that calcite crystals bind soil particles together. In the laboratory loose, liquefiable sand can be transformed into sandstone-like material in a matter of days. MICP is also attractive in that it uses less energy, and may be more sustainable than existing technologies using man-made chemicals. This research project is up-scaling the technology towards full-scale field deployment. Focus is placed on particular issues that directly influence the cost, environmental impact, sustainability, uniformity, and permanence. These issues include stimulation and utilization of naturally existing soil bacteria, optimization of treatment formulation, and optimization of the physical injection technique. This will be studied through a combination of numerical and experiment work across length scales from about 10 cm up to 5 m.

生物介导的土壤改良，特别是微生物诱导方解石沉淀（MICP）作为一种天然的生物介导的胶结过程，用于砂的改良，已经取得了迅速的进展。我们建议通过实验和数值模拟技术支持的适度的现场规模试验，直接解决治疗均匀性验证，生物刺激和副产品管理的关键问题。 具体而言，我们建议在一个深试验室使用天然可膨胀砂进行两个现场规模的试验。 第一次试验依赖于生物增强（注射细菌），以提供一组低风险的地面实况数据，不受我们在生物刺激中面临的天然细菌未知空间分布的影响。这第一个实验直接建立在广泛的实验室研究基础上，成功的可能性很高，因此将重点放在处理均匀性和使用现场和实验室土工试验进行验证上。第二项试验将使用生物刺激（激活原生固着细菌），引入额外的自由度（细菌的空间分布），但也是未来最理想的现场规模处理方法。 它更实用（成本，允许），减少了副产品的产生，并可能增加均匀性。 这两项试验将使研究的副产品产生过程中的处理和土壤改良后的命运。我们认为，在一个大型试验箱中进行现场规模的处理，可以在长度规模和实验控制之间提供必要的平衡，以严格但实际地解决这些问题。全面的工作将得到开发强大的生物刺激技术和现场试验建模的并行努力的支持，以开发一种预测建模工具，该工具考虑了生物刺激，副产品运输和命运以及空间异质性。 范围建立在团队上？在过去的八年里，我们继续开展研究活动，使这成为一个具有挑战性但可行的范围。 我们设想，该项目的成功完成将通过改善治疗均匀性、验证测试的确认、生物刺激方法的开发以及管理副产品的产生和命运而具有变革性。生物介导土壤改良是一种相对较新的、新颖的技术，用于将土壤的工程性质改善到可以支持民用基础设施的水平。 特别是微生物诱导的方解石沉淀（Microbially Induced Calcite Precipitation，简称MICP），是土壤中的微生物活动暂时改变当地环境条件，使方解石晶体将土壤颗粒结合在一起的过程。 在实验室中，松散的可液化砂可以在几天内转化为类似砂岩的物质。 微污染控制项目的吸引力还在于它使用较少的能源，而且可能比使用人造化学品的现有技术更具可持续性。 该研究项目正在将该技术扩大到全面的实地部署。 重点放在直接影响成本，环境影响，可持续性，一致性和持久性的特定问题上。 这些问题包括自然存在的土壤细菌的刺激和利用，处理配方的优化，以及物理注入技术的优化。 这将通过数值和实验工作相结合的长度尺度从约10厘米到5米进行研究。