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

在本项目中，我们将探索和评估生物介导的地基加固技术的潜力，以（1）改善有限区域土壤的工程特性（即强度，刚度）和（2）修复施工方法损坏的土壤区域。 前一个目的与其他传统灌浆技术相似（例如，处理不适合施工性能的大面积有限土壤区域），而后一个目的可用于处理在安装过程中受到损坏（例如，压碎、脱水泥）的施工构件（例如，桩）附近的土壤。 在这两种情况下，首要目标都是通过改善？薄弱环节？在负载转移机制中。 在这个项目中，我们的目标是推进一个生物介导的技术，诱导方解石沉淀颗粒土壤。 我们将继续开发一种好氧工艺，其可行性已在实验室中由PI和其他人建立，并探索一种具有相同沉淀方解石最终产品的平行厌氧工艺。 将调查处理过程的生物方面，包括长期持久性、处理优化和环境影响。 在毫米到厘米的长度尺度上，我们将研究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，对静态和循环载荷的响应在一系列应变幅度范围内的变化，以及土壤-结构界面剪切。 最后，我们建议进行m长度的规模模型测试的注射可行性的处理有限区域的土壤和处理立即周围的桩使用楔形室，准确地复制径向流和扩散从线注射源在原位。这将能够以较低的成本评估全规模现场注入的可行性，并在现场对注入过程进行局部测量。 该研究计划旨在将生物处理方法从概念验证推进到成熟，以激励政府机构和行业继续发展。 教育，推广和培训活动跨越K-16+学生，教师和研究人员。 研究小组与一家著名的科学和工程教育教科书出版公司合作，开发课堂讲座模块和实验练习。 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.