Collaborative Research: Strength of Clay Shale in Relation to Mineralogy, Micromorphology and Pore Water Chemistry

摘要：超固结粘土和粘土页岩为工程师提供了一些最具挑战性的岩土工程问题，通常涉及滑坡和膨胀行为。据估计，以2000年的美元计算，山体滑坡给美国公共和私人实体造成的平均年度直接和间接经济损失超过30亿美元。在美国大陆，受滑坡和膨胀土壤影响最严重的地区恰好是过度固结粘土和粘土页岩的所在地，包括阿巴拉契亚山脉地区、从德克萨斯州到北达科他州的中西部大草原和落基山脉的前缘。近年来，在了解矿物学和系统化学对超固结粘土和粘土页岩行为的作用方面取得了相当大的进展。特别是，已经观察到，材料的风化作用加上土壤系统孔隙水化学的变化会导致土壤强度的显著降低。在这项研究中，将以南达科他州的皮埃尔页岩为试验材料，对与粘土页岩风化有关的物理化学变化进行基本调查。目的是确定伴随皮埃尔页岩风化过程的矿物学、微观形态和孔隙水化学的变化，并将这些变化与剪切强度的降低联系起来。如果对这些过程有更好的了解，就可能更容易查明易受强度损失影响的材料，并设计出更有效的缓解措施。根据本研究中形成的概念性理解，预计可以制定改进页岩斜坡的施工和缓解程序的建议。页岩是土建工程中最常见的土质材料之一。因此，这项研究的结果可能会对社会产生重大影响，因为它可以降低与水坝、桥梁和高速公路等公共工程以及住房开发和商业地产等私人项目相关的成本。

CMS-0201482PI: Vernon SchaeferInstitution: South Dakota State UniversityTitle: "Collaborative Proposal for Research on the Strength of Clay Shale in Relation to Mineralogy, Micromorphology, and Pore Water Chemistry"AbstractOverconsolidated clays and clay shales provide engineers with some of their most challenging geotechnical problems, generally involving landslides and expansive behavior. It has been estimated that the average annual direct and indirect economic cost of landslides to public and private entities in the United States is over $3 billion in 2000 dollars. The areas most affected by landslides and expansive soils in the continental United States coincide with locations of overconsolidated clays and clay shales, including the Appalachian Mountains region, much of prairies of the Midwest from Texas to North Dakota, and the front range of the Rocky Mountains. In recent years considerable advances have been made in understanding the role of mineralogy and system chemistry on the behavior of overconsolidated clays and clay shales. In particular, it has been observed that weathering of the materials combined with changes in the pore water chemistry of the soil system can lead to significant reductions in the soil's strength. In this study a fundamental investigation of the physiochemical changes associated with the weathering of clay shales will be undertaken, using the Pierre shale of South Dakota as the test material. The objective is to identify changes in mineralogy, micromorphology and pore water chemistry that accompany the weathering processes of the Pierre shale and to correlate these changes with the reduction in shear strength. If these processes are better understood, it is likely that materials susceptible to strength loss can be more readily identified and that more effective means of mitigation can be devised. Based on the conceptual understanding developed in this research it is anticipated that recommendations for improved construction and mitigation procedures for shale slopes can be developed. Shale is one of the most commonly encountered earth materials in civil construction works. Hence, the results of this research may have a significant impact to society in terms of reduced costs associated with public works including dams, bridges and highways, as well as private projects such as housing developments and commercial properties.