BIOLOGICALLY DRIVEN SOIL IMPROVEMENT

生物驱动的土壤改良奖摘要（奖项# 0528171）生物过程可能为原位，成本有效的土壤改良提供巨大的和以前未开发的机会。这项研究将评估以前未经测试的自然发生的微生物序列，这些序列可能被操纵以显着提高土壤的强度和刚度。旨在复制的过程是当碳酸钙在颗粒土壤中沉淀时发生的自然过程，从而产生牢固的胶结土壤。在自然环境中，钙的化学沉淀在有氧条件下很容易发生。此外，众所周知，好氧细菌可以通过从环境中吸收阳离子来诱导土壤中存在的钙的沉淀，因为它们的表面带负电荷。由于这些过程，钙的沉淀产生碳酸钙沉淀物。这个过程中产生的沉淀物是高度不溶的，可以预期通过被吸附到单个土壤颗粒上，从而导致它们的强胶结，从而大大增加土壤的强度。这项探索性研究的目的是通过实验室实验项目了解在原位重现这一自然过程所需的条件，从而对土壤特性产生有利影响。首先，这将包括调查各种因素的影响，如方解石氧化细菌的相对浓度、过程每个阶段的持续时间、土壤强度的改善或退化，以及水力导电性的可能变化。这一过程最终可用于施工前的场地准备，例如地面或地下建筑，或用于修复被认为土壤条件不足的现有场地，包括易受地震影响的土壤。当前研究的更广泛影响包括改善易受地震影响的土壤和在关键应用（如军事行动）期间的快速建设。PI将从代表性不足的群体中聘请本科生研究助理在实验室工作，旨在实现学术背景的多样性。PI已经在他的研究学生中建立了多样性的承诺，他的经验表明，参与研究的本科生更有可能继续研究生学习。

Biologically Driven Soil ImprovementAward Abstract(Award # 0528171) Biological processes may provide great and previously unexplored opportunities for in situ, cost effective soil improvement. This research study will evaluate previously untested naturally occurring microbiological sequences that may be manipulated to dramatically improve the strength and stiffness of soil. The process aimed to replicate is the natural process that occurs when calcium carbonate precipitates in granular soil, resulting in a strongly cemented soil. Chemical precipitation of calcium occurs readily under aerobic conditions in a natural environment. In addition, it is known that aerobic bacteria can induce precipitation of the calcium present in the soil by drawing cations from the environment due to their negative surface charges. As a result of these processes, precipitation of calcium produces calcium carbonate precipitates. The precipitates arising from the process are highly insoluble and can be expected to increase the strength of the soil substantially by being adsorbed onto individual soil particles, leading to their strong cementation. The purpose of this exploratory research is to understand through a laboratory experimental program the conditions needed to recreate this natural process in situ with resulting advantageous effects on soil properties. To begin with, that would include investigating the impact of factors such as relative concentrations of calcite-oxidizing bacteria, the duration of each stage of the process, as well as the resulting improvement or degradation in soil strength, and possible changes in hydraulic conductivity. This process could ultimately be used either for site preparation before construction, for example, of either surface or underground construction, or for remediation of existing sites with soil conditions considered to be inadequate, including in earthquake susceptible soils. The broader impacts of the immediate study include improvement of earthquake susceptible soils and rapid construction during critical applications, such as military operations. The PI will hire undergraduate research assistants from underrepresented groups to work in the laboratory, aiming for diversity of academic background also. The PI has established a commitment to diversity among his research students and his experience has shown that undergraduates involved in research are more likely to continue onto graduate study.