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

该奖项是NSF 08-519项目征集“小乔治·E·布朗地震工程模拟(NEES)研究网络(NEESR)”竞赛的结果，包括加州大学戴维斯分校(牵头机构)和拉斐特大学(分奖机构)。该项目将利用加州大学戴维斯分校的NEES设备现场，其中包括一台最先进的岩土离心机(http://nees.ucdavis.edu).我们的项目愿景是评估和确定生物中介的地基改良过程的潜力，以增加土壤对液化触发的抵抗力，并减少周围土壤发生液化时的后果。将实施的生物介导式地基改良过程利用自然产生的微生物的生物活性来创造方解石晶体形成并将土壤颗粒结合在一起所需的环境条件(www.sil.ucdavis.edu)。这一过程类似于沙的自然地质过程，并产生类似的结果，即类砂岩物质。生物中介方法很有吸引力，因为它是一个自然发生的过程，只是被加速了。在这个项目中，我们将研究生物中介土壤改良方法处理可液化土壤如何防止/限制液化的发生，以及在生物改良土壤上支撑的建筑物的性能。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规模化结构(建筑物)。建筑物正下方的土壤区域将进行处理。然后，通过旋转离心机，模型将受到现场(真实)尺度应力条件的影响。在旋转过程中，模型将受到地震震动，除了高速视频外，还将使用位移、孔压和加速度计传感器来测量土壤和结构的性能。这项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。它也代表着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一个新兴领域。除了提供对减轻与可液化土壤相关的危害的直接洞察之外，生物介导的地基改良过程在未来的大坝和堤坝安全、隧道施工、环境屏障、地下水保护、含水层储存、能量储存和地质二氧化碳封存方面具有潜力。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数据库(http://www.nees.org).)提供

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).