NEESR-II: Biological Improvement of Sands for Liquefaction Prevention and Damage Mitigation

该奖项是NSF 08-519项目征集的结果。小布朗地震工程模拟网络（NEES）研究（NEESR）竞赛，包括加州大学戴维斯分校（牵头机构）和拉斐特大学（子奖项）。该项目将利用位于戴维斯的加州大学的NEES设备场地，其中包括一台最先进的土工离心机（http：nees.ucdavis.edu）。我们的项目愿景是评估和建立一个生物介导的地基加固过程的潜力，以增加土壤抗液化触发和减少的后果，如果液化确实发生在周围的土壤。 将实施的生物介导的地面改良过程利用自然存在的微生物的生物活性来创造方解石晶体形成和将土壤颗粒结合在一起所必需的环境条件（www.sil.ucdavis.edu）。 这一过程类似于砂的自然地质过程，并产生类似的结果，即砂岩状物质。 生物介导的方法是有吸引力的，因为它是一个自然发生的过程，只是被加速。在这个项目中，我们将研究如何处理可液化的土壤与生物介导的土壤改良方法防止/限制液化的发生和建筑物的性能支持生物改良土壤。 加州大学戴维斯分校的NEES离心机设施将用于建造支撑在可液化土壤上的成比例结构（建筑物）。 建筑物正下方的土壤区域将得到处理。 然后通过旋转离心机使模型经受场（真实的）尺度应力条件。 在旋转过程中，模型将受到地震震动，土壤和结构的性能将通过位移、孔隙压力和加速度计传感器以及高速视频进行测量。 这种跨学科的研究有可能改变减轻地震对民用基础设施造成的破坏的方式。 它也是对生物土壤工程领域的重大贡献，生物土壤工程是土木工程，微生物学和地球化学交叉的新兴领域。 除了提供直接洞察到减轻与可液化土壤相关的危害，生物介导的地基改良过程在未来有可能用于大坝和堤坝安全，隧道，环境屏障，地下水保护，含水层储存，能量储存和地质CO2封存。 该项目还将参与这一新的跨学科领域的本科生和研究生的教育和培训。 该项目的数据将通过NEES数据储存库（http：//www.example.com）提供。www.nees.org

This award is an outcome of the NSF 08-519 program solicitation ''George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)'' competition and includes the University of California at Davis (lead institution) and Lafayette University (subaward). The project will utilize the NEES equipment site at the University of California at Davis, which consists of a state-of-the-art geotechnical centrifuge (http://nees.ucdavis.edu). Our project vision is to evaluate and establish the potential of a bio-mediated ground improvement process to increase soil resistance to liquefaction triggering and to reduce the consequences if liquefaction does occur in the surrounding soil. The bio-mediated ground improvement process that will be implemented utilizes the biological activity of naturally occurring microbes to create the environmental conditions necessary for calcite crystals to form and bind soil particles together (www.sil.ucdavis.edu). This process is akin to the natural geologic process of sands and produces similar results, namely sandstone-like material. A bio-mediated approach is attractive since it is a naturally occurring process that is simply being accelerated.In this project we will examine how the treatment of liquefiable soils with the bio-mediated soil improvement method prevents/limits the occurrence of liquefaction and the performance of buildings supported on bio-improved soil. The UC Davis NEES centrifuge facility will be used to create scaled structures (buildings) supported on liquefiable soils. Zones of the soil directly beneath the building will be treated. The model will then be subjected to field (real) scale stress conditions by spinning the centrifuge. During spinning the models will be subjected to earthquake shaking and the performance of the soil and the structure will be measured with displacement, pore pressure, and accelerometer transducers in addition to high-speed video. This interdisciplinary research has the potential to transform the way in which earthquake-induced damage to civil infrastructure is mitigated. It also represents a significant contribution to the field of bio-soil engineering, a new emerging field at the cross-roads of civil engineering, microbiology, and geochemistry. In addition to providing direct insight into mitigating hazards associated with liquefiable soils, bio-mediated ground improvement processes have the potential in the future for dam and levee safety, tunneling, environmental barriers, groundwater protection, aquifer storage, energy storage, and geologic CO2 sequestration. The project will also be involved in the education and training of undergraduate and graduate students for this new interdisciplinary field. Data from this project will be made available through the NEES data repository (http://www.nees.org).