Acquisition and Development of Equipment for Unsaturated Soil Research

俄克拉荷马大学（OU）土木工程与环境科学学院（CEES）将购买和开发最先进的设备，用于与非饱和土壤行为相关问题的综合研究/教育。在土木工程界，部分饱和近地表土的特性正受到强烈的研究兴趣。边坡破坏、路堤沉降、膨胀粘土引起的地基隆起、路面路基性能、化学品泄漏和渗漏带修复，只是一些普遍存在的工程问题的例子，其解决方案取决于对非饱和土行为的理解。由于教师的专业知识和在非饱和土力学方面已经建立的引人注目的研究，CEES准备成为这一领域的领导者。通过NSF核磁共振基金获得的设备将使研究人员能够以目前不可能的方式深入检查，理解和定义非饱和土壤的行为。将获得和开发5台非饱和土测试设备：1)购买直剪试验装置，并建造一个独特的测试单元/设备，用于控制和/或测量孔隙空气和孔隙水压力。测试单元将容纳土壤-土壤或土壤-建筑材料界面的测试。2)将购买用于检查土壤应力-应变行为的定制中空圆柱体设备，并将在施加于土壤的应力和应变路径上提供完全的自由。该装置允许中空圆柱体试样承受轴向力和扭矩，以及不同的内部和外部细胞压力。此外，孔隙空气和孔隙水压力可以控制。这些力和压力是由PC独立控制的。因此，可以控制三个主应力的大小和方向。将包括数据采集，并将制作压力控制面板。3)将购买一个压力计，并建造一个测试单元，用于控制和/或测量孔隙空气和孔隙水压力。数据采集和压力控制面板将被制造出来。该设备将允许测定非饱和土壤的基本一维压缩特性。(4)中国工程院目前拥有的一个立方体装置，可以独立控制非饱和土立方体三轴试验中主应力方向上施加的总正应力。除了位移测量外，还可以测量孔隙空气和孔隙水压力，以及自动应用循环载荷。5)为快速、详细地测量土壤中空气/水和有机-液体/水毛细管压力-饱和度关系和相对渗透率，将构建一个并联微型压力单元系统。该系统将由8个定制的微型压力单元并行运行，以及一个用于自动操作和数据采集的计算机控制系统组成。通过MRI拨款获得的设备将大大提高当前的研究能力，并使CEES成为非饱和土壤行为领域的卓越研究机构。目前，美国还没有这种类型的独特中心，因此新的设施将具有广泛的吸引力。俄勒冈州立大学成为一个杰出的非饱和土壤研究中心是合适的，特别是考虑到困扰俄克拉荷马州和其他周边州（如德克萨斯州和科罗拉多州）的众多非饱和土壤问题。

The School of Civil Engineering and Environmental Science (CEES) at the University of Oklahoma (OU) will purchase and develop state-of-the-art equipment for integrated research/education in problems associated with unsaturated soil behavior. Within the civil engineering community, behavior of partially saturated near-surface soils is receiving intense research interest. Slope failures, embankment settlement, foundation heave due to expansive clays, pavement subgrade performance, chemical spills, and vadose zone remediation, are just a few examples of prevalent engineering problems whose solution depends on understanding unsaturated soil behavior. The CEES is poised to be a leader in this field due to the expertise of the faculty and the compelling research already established in unsaturated soil mechanics. Equipment obtained via NSF MRI funding will enable researchers to examine in-depth, comprehend, and define unsaturated soil behavior in ways not currently possible. Five pieces of equipment for testing unsaturated soils will be acquired and developed: 1) A direct shear test device will be purchased and a unique test cell/apparatus will be constructed for control and/or measurement of pore-air and pore-water pressure. The test cell will accommodate testing of soil-to-soil or soil-to-construction material interfaces. 2) A custom made hollow cylinder apparatus used for examining stress-strain behavior of soil will be purchased and will provide complete freedom on the stress and strain paths applied to the soil. The apparatus allows a hollow cylinder test specimen to be subjected to axial force and torque, and to different internal and external cell pressures. In addition, pore air and pore water pressures can be controlled. These forces and pressures are controlled independently from a PC. Accordingly, it is possible to control the magnitude and direction of the three principal stresses. Data acquisition will be included, and a pressure control panel will be fabricated. 3) An oedometer will be purchased and a test cell will be constructed for control and/or measurement of pore-air and pore-water pressure. Data acquisition will be acquired and a pressure control panel will be fabricated. The equipment will allow for the determination of fundamental one-dimensional compression properties of unsaturated soils. 4) A cubical device, currently owned by CEES, permits independent control of total normal stress applied in the principal stress directions during cubical triaxial testing of unsaturated soil. Modifications will allow measurement of pore air and pore water pressure, and automated application of cyclic loads, in addition to measurement of displacements. 5) A parallel miniature pressure cell system will be constructed for rapid, detailed measurement of air/water and organic-liquid/water capillary pressure-saturation relationships and relative permeabilities in soils. The system will be comprised of eight custom-built miniature pressure cells operated in parallel, and a computerized control system for automated operation and data acquisition.Equipment obtained through the MRI grant will greatly enhance current research capabilities and allow CEES to become a preeminent research institution in the area of unsaturated soil behavior. Currently, there is no unique center of this type in the United States, and thus the new facilities will have broad appeal. It is fitting that OU becomes the location of a preeminent research center for unsaturated soils, particularly in light of the numerous unsaturated soil problems that plague Oklahoma and other surrounding states such as Texas and Colorado.