Exploratory Research in Microbial Remediation of Liquefiable Soils

可液化土壤微生物修复的探索性研究

• 批准号: 0408832
• 负责人: Mary Roth
• 金额: $ 5.61万
• 依托单位: Lafayette College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-02-01 至 2006-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0408832&HistoricalAwards=false
• 关键词: Exploratory; Research; Microbial; Remediation; Liquefiable

Saturated loose sand deposits subjected to seismic loads are susceptible to liquefaction, a phenomenon in which there is a rapid loss of strength of the soil caused by a sudden increase in porewater pressure. Structures built on these soils may suffer severe deformations or failure during liquefaction due to excessive settlement caused by the loss of support from the foundation soils. At undeveloped sites, proven methods of soil improvement - e.g., dynamic compaction and vibro-compaction - can reduce the likelihood of liquefaction. However, at locations where structures already exist or exist nearby, these methods are either impossible to implement or are impractical as they may cause damage to these structures.The aim of this research is to determine whether the addition of bacteria, either simple adhering bacteria or biofilm formers, increases the strength and stability of liquefiable soils. It is hypothesized that the microbes will provide some cohesion/cementation between the particles, thereby increasing their resistance to liquefaction. Very little research has been done on the use of microbes to improve the strength properties of soil. Loose sands will be inoculated in separate tests with two organisms, Cytophaga U67 (a biofilm former) and a mutant Cytophaga U67 (a non-biofilm former). Cytophaga are naturally found in a saturated, low-nutrient environment. The attachment of the microbe to the solids is expected to create cohesion/cementation between particles, thereby reducing the susceptibility of the soil deposit to loss of strength during rapid increases in porewater pressure. Cohesive strength gains in the sand will be measured using vane shear tests and/or unconfined compression tests.This project will provide information on the potential use of microbes in the remediation of liquefiable soils. It will also initiate the first collaborative research project between the civil engineering and biology departments at Lafayette College. The results will be disseminated to the wider scientific community through poster presentations and published research papers.

承受地震载荷的饱和松散的沙子沉积物容易受到液化的影响，在这种现象中，由于孔隙水压突然增加，土壤强度迅速损失。 建立在这些土壤上的结构可能会因由于基础土壤失去支撑而导致的过度沉降，因此在液化过程中可能遭受严重的变形或故障。 在未开发的地点，有经过验证的土壤改善方法 - 例如，动态压实和振动散发 - 可以降低液化的可能性。 但是，在结构已经存在或附近存在的位置，这些方法要么无法实施或不切实际，因为它们可能会对这些结构造成损害。这项研究的目的是确定细菌的添加是是否添加了简单的粘附细菌或生物膜形成者，会增加液化土壤的强度和稳定性。 假设微生物将在颗粒之间提供一些内聚/胶结，从而增加了它们对液化的耐药性。 关于使用微生物来改善土壤的强度特性的研究很少。 散发的沙子将与两种生物体的单独测试接种，分别是细胞增生的U67（以前的生物膜）和一个突变的细胞胞质U67（曾经的非生物胶片）。 细胞吞噬自然是在饱和，低营养的环境中发现的。 预计微生物在固体上的附着会产生颗粒之间的内聚/胶结，从而降低了土壤沉积物对孔隙水压迅速增加强度损失的敏感性。 将使用叶片剪切测试和/或无限制的压缩测试来测量沙子中的粘性强度增长。本项目将提供有关微生物在修复液化土壤中潜在使用的信息。 它还将启动拉斐特学院土木工程和生物学系之间的第一个合作研究项目。 结果将通过海报演示和发表的研究论文传播给更广泛的科学界。