Acquisition and Development of Equipment for Unsaturated Soil Research

俄克拉荷马州大学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的问题的综合研究/教育。在土木工程界，部分饱和近地表土壤的行为受到强烈的研究兴趣。边坡破坏、路堤沉降、膨胀性粘土引起的地基隆起、路面路基性能、化学品泄漏和包气带修复只是普遍存在的工程问题的几个例子，这些问题的解决取决于对非饱和土特性的理解。由于教师的专业知识和在非饱和土力学中已经建立的引人注目的研究，CEES有望成为这一领域的领导者。通过NSF MRI资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研究，理解和定义非饱和土壤行为。将获得和开发五件用于测试非饱和土的设备：1）将购买直接剪切试验装置，并将建造独特的测试单元/仪器，用于控制和/或测量孔隙空气和孔隙水压力。试验单元将适应土壤与土壤或土壤与建筑材料界面的试验。2)将购买用于检查土壤应力-应变行为的定制空心圆柱体装置，该装置将提供施加于土壤的应力和应变路径的完全自由度。该装置允许中空圆柱体试样经受轴向力和扭矩，以及不同的内部和外部单元压力。此外，可以控制孔隙空气和孔隙水压力。 这些力和压力由PC独立控制。因此，可以控制三个主应力的大小和方向。 将包括数据采集，并将制造压力控制面板。3)将购买一个固结计，并建造一个试验室，用于控制和/或测量孔隙空气和孔隙水压力。将采集数据并制造压力控制面板。该设备将允许非饱和土壤的基本一维压缩特性的测定。4)一个立方体装置，目前拥有的CEES，允许独立控制的总法向应力施加在主应力方向在立方三轴试验的非饱和土。 修改将允许孔隙空气和孔隙水压力的测量，以及循环载荷的自动应用，除了位移的测量。 5)将建造一个平行的微型压力传感器系统，用于快速、详细地测量土壤中的空气/水和有机液体/水毛细管压力-饱和度关系和相对渗透率。 该系统将由八个定制的微型压力传感器并行操作，和一个计算机控制系统，自动操作和数据采集。通过MRI赠款获得的设备将大大提高目前的研究能力，使CEES成为一个卓越的研究机构在非饱和土行为的领域。 目前，在美国还没有这种类型的独特中心，因此新设施将具有广泛的吸引力。 这是合适的，科罗拉多州成为一个卓越的非饱和土壤研究中心的位置，特别是鉴于众多的非饱和土壤问题，困扰俄克拉荷马州和其他周边国家，如得克萨斯州和科罗拉多。

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.