BRIGE: Improving Resiliency of Coastal Systems using Bio-Mediated Soil Improvement & Promoting Women in Engineering

背景：沙丘是我们沿海环境的宝贵地质特征。在2012年飓风桑迪期间，受沙丘保护的沿海基础设施受到的破坏要比未受保护的基础设施少得多。沙丘自然地抑制来自大浪作用的能量，防止内陆的破坏和侵蚀。巨浪和高海平面侵蚀着支撑沿海生命线的沙质土壤，包括桥梁、高速公路、管道和其他公用设施。这些大型风暴事件造成的破坏可能导致严重的财产损失、收入损失和巨额维修费用。防止沙质土壤的侵蚀可以通过最大限度地减少破坏，降低修复成本并使社区在风暴事件发生后更快地恢复，从而提高这些沿海系统的恢复能力。目前减少海岸侵蚀的方法，如硬化结构、增加向下漂移侵蚀和用人工基础设施取代自然环境。海岸沙丘也是海岸生态的重要组成部分；因此，加固可蚀性沙质土壤的过程不应破坏沿海自然生态。技术描述：拟建项目将为沿海社区脆弱的生命线提供一种新的土壤改良方法。将MICP处理方法应用于海岸沙丘，需要评估在新的荷载条件下改善的土壤性质，并评估处理过程对周围生态的影响；因此，推进生物介导的土壤改良知识。微生物诱导方解石降水（microinduced Calcite Precipitation， MICP）在保护沙丘自然生态的同时，具有加固海岸沙丘的作用。MICP利用尿素水解和氯化钙作为化学反应，增加孔隙流体的碱度，诱导方解石析出。巴氏孢杆菌是一种常见的嗜碱土壤细菌，具有较高的脲酶活性，用于促进化学反应。MICP过程自然发生在原位将砂胶结到砂岩中；然而，它可以被利用和加速，作为一个自然的土壤改善过程。评估MICP用于保护沿海系统的能力将通过解决以下目标来实现：1)设计适合沿海土壤的MICP处理过程，2)评估抗剪强度的增加和侵蚀潜力的减少，3)解决MICP处理过程可能对沿海生态产生的潜在影响（不利或有利）。更广泛的意义和重要性：全球一半以上的人口居住在沿海社区附近，这些社区在大风暴事件后往往难以恢复。拟议的项目旨在通过开发新的可持续处理方法来促进生物介导的土壤改良，同时最大限度地减少对极端负载条件的处理。对当地生态的影响。通过实施该项目中开发的处理过程，生命线将能够抵御大型风暴事件的负荷，同时保护自然环境，这将提高沿海基础设施的弹性。在更广泛的背景下，该项目的科学进展也将适用于液化预防、边坡稳定性问题和巷道支护。扩大未被充分代表的群体在工程领域的参与：在生物介导的土壤改良研究的同时，还设计了一个推广计划，以促进女学生在工程领域的职业发展。社会将从女性工程师的增加中受益，因为它提供了一个不同的视角来解决今天的问题？年代的挑战。该项目的多样性相关目标包括增加年轻女学生对工程学的兴趣，增加女大学生进入研究生课程和学术生涯的招聘和保留。这一目标将通过让女学生接触不同的工程职业道路来实现，并通过为学生在小学、中学和大学教育中提供女性工程榜样来实现。这项研究是由工程教育和中心部的工程项目扩大参与计划的一部分，即工程项目扩大参与研究启动基金资助的。

Background:Sand dunes are an invaluable geologic feature of our coastal environment. During Hurricane Sandy in 2012, coastal infrastructure protected by sand dunes had much less damage than the infrastructure that was not protected. The sand dunes naturally dampen the energy from the large wave action and prevent damage and erosion further inland. Large wave action and high sea levels erode the sandy soil that supports coastal lifelines, including bridges, highways, pipelines, and other utilities. Damage from these large storm events can result in severe property damage, loss of revenue, and large repair costs. Preventing the erosion of the sandy soil can improve the resiliency of these coastal systems by minimizing damage, reducing repair costs and allowing communities to recover quicker after the storm events. Current methods to reduce coastal erosion, such as hardened structures, increase down drift erosion and replace the natural environment with man-made infrastructure. Coastal sand dunes are also an integral part of the coastal ecology; therefore a process used to reinforce the erodible sandy soil should not disrupt the natural coastal ecology. Technical Description: The proposed project will provide a new soil improvement method to reinforce vulnerable lifelines in coastal communities. Applying MICP treatment methods to coastal sand dunes will require assessing the improved soil properties under new loading conditions and evaluating the effect the treatment process has on the surrounding ecology; hence, advancing the knowledge of bio-mediated soil improvement.Microbial Induced Calcite Precipitation (MICP) has the potential to reinforce coastal sand dunes while preserving the natural ecology of the dunes. MICP utilizes urea hydrolysis with calcium chloride as the chemical reaction to increase the alkalinity of the pore fluid and induce calcite precipitation. Sporosarcina pasteurii, a common alkalophilic soil bacterium, has a high urease activity and is used to facilitate the chemical reaction. The MICP process occurs naturally in situ cementing sand into sandstone; however, it can be harnessed and accelerated to be used as a natural soil improvement process. Assessing the ability for MICP to be used to protect coastal systems will be achieved by addressing the following objectives: 1) designing a MICP treatment process suitable for coastal soils, 2) evaluating the increase in shear strength and reduction of erosion potential, 3) addressing the potential effects (either adverse or beneficial) the MICP treatment process may have on the coastal ecology. Broader Significance and Importance:Over half of the global population lives near coastal communities, and these communities often struggle to rebound after large storm events. The proposed project is developed to advance bio-mediated soil improvement by developing new sustainable treatment methods for extreme loading conditions while minimizing the treatment?s impact on the local ecology. With the implementation of the treatment process developed within this project, lifelines will be able to resist the loading from large storm events while preserving the natural environment, which will improve the resiliency of the coastal infrastructure. In the broader context, the scientific advances from this project would also be applicable for liquefaction prevention, slope stability concerns, and roadway support.Broadening Participation of Underrepresented Groups in Engineering: In parallel with the bio-mediated soil improvement research, an outreach program is designed to promote female students to pursue a career in engineering. Society will benefit from an increase in female engineers by providing a diverse perspective to solve today?s challenges. The diversity-related goals of this project include increasing the interest of engineering among young female students and increasing the recruitment and retention female university students into graduate programs and academic careers. This goal will be met by exposing female students to different career paths in engineering and by providing female engineering role models the students can connect to during their elementary, middle school, and university education.This research has been funded through the Broadening Participation Research Initiation Grants in Engineering solicitation, which is part of the Broadening Participation in Engineering Program of the Engineering Education and Centers Division.