Bio-Mediated Improvement of Soil and Soil-Structure Interface Behavior

在这个项目中，我们将探索和评估生物介导的地基改良技术的潜力，以(1)改善有限区域土壤的工程性质(即强度、硬度)和(2)修复被施工方法破坏的土壤区域。前者的用途与其他传统灌浆技术类似(例如处理大型有限土层，而这些土块不足以按建筑性能进行施工)，而后者则可用于处理在安装过程中受损(例如压碎、剥落)的紧邻建筑构件(例如打桩)的泥土。在这两种情况下，首要目标都是通过改进薄弱环节来提高构建系统的性能。在载荷传递机制中。在这个项目中，我们的目标是推进一种生物介体技术，即用颗粒状土壤诱导方解石沉淀。我们将继续开发一种好氧工艺，其可行性已由PIS和其他人在实验室中确定，并将探索一种使用相同沉淀方解石最终产物的并行厌氧工艺。将对处理过程的生物学方面进行调查，包括长期持久性、处理优化和环境影响。在毫米到厘米长的尺度上，我们将调查生物处理对土壤和土壤-结构界面行为的影响，检查材料状态、渗透性、在一定应变范围内对静态和循环载荷的响应以及土壤-结构界面剪切的变化。最后，我们建议使用楔形室进行m长比例尺模型试验，以测试处理有限区域土体和桩周围处理的可行性，该楔形室可以准确地复制现场直线注入源的径向流动和扩散。这将能够以更低的成本全面评估现场注入的可行性，并在现场不可能对注入过程进行本地化测量。这项研究计划旨在推动生物处理方法从概念验证到成熟，以激励政府机构和行业继续发展。教育、外展和培训活动涵盖了K-16+的学生、教师和研究人员。研究小组已与一家著名的科学和工程教育教科书出版公司合作，开发课堂讲课模块和实验室练习。NSF教师研究经验(RET)和本科生研究经验(REU)研究员将参与技术研究以及K-16+课程的开发。

In this project we will explore and evaluate the potential of a bio-mediated ground improvement technique to (1) improve the engineering properties (i.e. strength, stiffness) of a finite zone of soil and (2) heal zones of soil damaged by construction methods. The former purpose parallels other conventional grouting techniques (e.g. treatment of large finite zones of soil which are inadequate for construction on constructed performance), while the latter purpose could be used to treat soil in the immediate vicinity of construction elements (such as piling) which has undergone damage (e.g. crushing, decementation) during the installation process. In both cases, the overarching objective is to improve the performance of constructed systems through improving the ?weak link? in the load transfer mechanisms. Within this project our objective is to advance a bio-mediated technique which induces calcite precipitation with granular soils. We will continue the development of an aerobic process whose feasibility has been established in the laboratory by the PIs and others, and explore a parallel anaerobic process with the same precipitated calcite end product. Biological aspects of the treatment process will be investigated, including long-term permanence, treatment optimization, and environmental impact. At the mm-to-cm length scale we will investigate the influence of the bio-treatment on soil and soil-structure interface behavior, examining changes in material state, permeability, response to static and cyclic loading across a range of strain magnitudes, and soil-structure interface shear. Finally, we propose to perform m length scale model testing of the injection feasibility for treatment of a finite zone of soil and for treatment immediately around a pile using a wedge shaped chamber that accurately replicates radial flow and diffusion from a line injection source in situ. This will enable assessment of full scale field injection feasibility at reduced costs and localized measurements of the injection process not possible in the field. This research program is designed to advance the bio-treatment method from proof-of-concept to a maturity that would motivate government agencies and industry to continue its development. The education, outreach, and training activities span K-16+ students, teachers, and research faculty. The research team has linked with a prominent science and engineering education textbook publishing company to develop classroom lecture modules and laboratory exercises. NSF Research Experience for Teachers (RET) and Research Experience for Undergraduate (REU) fellows will be involved in technical research as well as in the K-16+ curriculum development.