Collaborative Research: Geotechnical Investigation of Bivalve-Sediment Interaction with regard to Bivalve Farms as a Self-sustained Scour Mitigation Method

在世界范围内，当结构基础位于自来水中或附近时，冲刷是一个严重的问题。 例如，美国桥梁故障的最常见原因是桥墩周围的冲刷。 先前的研究表明，双壳类群体通过不同的过程减少局部侵蚀，并且双壳类对强水流具有较高的抵抗力。 然而，目前关于双壳类群体对岩土海底参数的影响的知识存在空白。这阻碍了双壳类养殖场作为一种潜在的自我维持冲刷缓解方法的评估和发展。 这项基础研究将通过现场和实验室测试来解决这一知识差距。 通过这种方式，这项研究将代表着使用双壳类养殖场作为缓解冲刷策略的关键一步，并推动沿海环境生物地球工程领域的发展。在该项目的框架内，将启动新的跨学科、国内和国际合作，多名研究生和本科生将受益于这一创造性、跨学科和国际项目的参与。 该项目还将通过强调招收女学生和来自不同社会经济背景的学生来寻求增加岩土工程领域的多样性。该项目将测试以下工作假设：H1）双壳类群体的存在减少了当地的冲刷和侵蚀。 H2) 双壳类菌落形成适用于冲刷保护设计的形态。 H3) 双壳类粘附蛋白增加沉积物强度并降低侵蚀性。 H4) 双壳类从土壤表面脱落发生为“块故障”？对于单个双壳类动物，但对于双壳类动物群体来说，与侵蚀问题无关。 这些假设将通过跨学科和多方法的方法进行测试，其特点是：（i）在弗吉尼亚州和北卡罗来纳州的两个双壳类群体地点进行实地调查，（ii）双壳类群体形态和流动阻力与现代冲刷保护设计的分析比较，以及实验室测试调查（iii）双壳类粘附蛋白与沉积物混合导致的沉积物强度和可蚀性的变化，以及（iv）双壳类移动过程中的土壤破坏行为。 这项研究可能为水下环境中仿生岩土工程和冲刷防护的新方向铺平道路。 在更窄的范围内，该项目将提供信息，并解决与多个学科和研究界（岩土工程、生物学、生态学、环境工程、水产养殖开发商）相关的知识差距。 它将通过提供新颖的岩土工程视角来补充现有的描述双壳类栖息地及其在风暴事件期间海岸保护中的作用的努力。 它还将使人们对双壳类移位过程有新的认识。 根据对 PI 的最佳了解，将首次测试贻贝粘附蛋白，以评估其对土壤力学特性的影响。 研究结果可能为以可持续方式临时土壤改良提供新方向。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Scour is a serious problem throughout the world where structural foundations are in or adjacent to running water. For example, the most common cause for bridge failures in the U.S. is scour around bridge piers. Previous studies have suggested that bivalve colonies reduce local erosion through different processes, and that bivalves feature a high resistivity to strong flow. However, there exists a current gap in knowledge regarding the impact of bivalve colonies on geotechnical seabed parameters. This hampers the assessment and development of bivalve farms as a potentially self-sustained scour mitigation method. This fundamental study will address this gap in knowledge by use of field and laboratory testing. In this way, the study will represent a crucial step towards the use of bivalve farms as a scour mitigation strategy, as well as advance the field of bio-geo-engineering in coastal environments. In the framework of this project, new interdisciplinary, domestic and international collaborations will be initiated, and multiple graduate and undergraduate students will benefit from participation in this creative, interdisciplinary and international project. The project will also seek to increase diversity in the field of geotechnical engineering by emphasizing the recruitment of female students and students from diverse socioeconomic backgrounds.The project will test the following working hypotheses: H1) The presence of bivalve colonies reduces local scour and erosion. H2) Bivalve colonies form morphologies applicable to scour protection design. H3) Bivalve adhesive protein increases sediment strength and decreases erodibility. H4) Bivalve dislodgement from soil surfaces occurs as ?block failure? for single bivalves, but becomes irrelevant for erosion issues in the case of bivalve groups. These hypotheses will be tested through an interdisciplinary and multi-method approach featuring: (i) field investigations at two bivalve colony locations in Virginia and North Carolina, (ii) an analytic comparison of bivalve colony morphology and flow resistivity to modern scour protection designs, and laboratory tests investigating (iii) the change of sediment strength and erodibility resulting from mixing bivalve adhesive protein with sediment and (iv) soil failure behavior during bivalve dislodgement. The study may pave the way for a new direction in bio-inspired geotechnical engineering in submerged environments, and scour protection. In a narrower focus, the project will deliver information, and address knowledge gaps relevant for multiple disciplines and research communities (geotechnical engineering, biology, ecology, environmental engineering, aquaculture developers). It will complement existing efforts of characterizing bivalve habitats and their role in coastal protection during storm events by providing a novel geotechnical perspective. It will also enable new insights into the process of bivalve dislodgement. To the best knowledge of the PIs, mussel adhesive proteins will be tested for the first time to evaluate their impact on soil mechanical properties. The results may offer a new direction in temporary soil improvement in a sustainable manner.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.