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A set of solutions to the cohesive soil erosion problem were developed through this study. A first device, the Erosionometer, was developed to perform a quick and reliable test to determine the critical shear stress of soils. The Erosionometer is based on physical shearing of the soil surface and has been calibrated through comparison with piston flume measurements of critical shear stress for entrainment of various fluvial bed sediments. This device is portable, easy to deploy in the field and in the laboratory and allows engineers and researchers to cover a sizeable terrain by performing many tests in a short timeframe, with immediate results. A modification to the Erosionometer was made to allow for subjecting the soil sample to a pressure differential while testing for critical shear stress. The added functionality is intended for investigating the effect of pressure gradient on the erodibility of cohesive soils by allowing for the erosion test to be conducted under a high pressure head while the other face of the sample (away from the flow) is maintained at zero head. Testing demonstrated that a positive pressure gradient on the eroding side (high pressure on flow side) can significantly increase the critical shear stress of cohesive soils, which is in line with other research available in the literature. The results show a simple linear relation between pressure differential and critical shear stress. Practical implications of these results are discussed. A second device, the Erosion Rate Meter, or ERM, was developed to test cohesive soil samples to determine the rate of erosion under various levels of bed shear stress. This device, while being portable and fast to setup and run, is a very realistic simulation of the flow-bed interaction and allows for a direct measurement of bed shear stress on the soil sample and a precise measurement of the erosion rate. An obvious outcome of using the ERM is the easy development of erosion rate vs. bed shear stress relationships or models to characterize the different soils for design projects or further research. Of the 16 tested cohesive soils, all but two demonstrated a linear relation between erosion rate and bed shear stress. The testing systems and methods developed in this research provide a comprehensive solution to the erodibility of cohesive soils from investigation to design. Significant improvements are achieved over existing systems in the speed, reliability, accuracy, and cost of estimating the erodibility of cohesive soils.

Project Completion Report / OWRT Project No. A-059-ARIZ / Development of Asphalt Cushioned Plastic and Plastic Reinforced Asphalt Membranes for Seepage Control / Agreement No. 14-31-0001-5003 / Project Dates: July 1974-June 1975. / This project was concerned with laboratory equipment development, laboratory testing, construction equipment development and field investigation of the APAC (Asphalt-Plastic-Asphalt-Chip-Coated) water seepage barrier. The laboratory equipment that was designed and fabricated for the project included hydrostatic testing vessels, slope stability apparatus, and tensile testing grips. Three testing methods were utilized and evaluated in the APAC investigation. The first test method evaluated the hydrostatic puncture resistance of the asphalt-polyethylene combination. This test confirmed the hypothesis that the asphalt effectively increases the puncture resistance of the APAC membrane over that of plain polyethylene. The second test investigated the slope stability of a protective APAC chip seal. It was found that a typical 3/8 in. (9.5 mm) cover aggregate remained stable on constructed slopes of 3:1 and 4:1 and that the 2:1 slope remained stable up to a surface temperature of 1220F (500C). The third test method evaluated adhesive materials and indicated that Presstite mastic was the best suited adhesive for sealing polyethylene overlaps. Subsequent field investigations resulted in equipment development that increased construction efficiency in the installation of the APAC membrane. Actual completed field installations were evaluated and further recommendations are included.

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Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1986. / Includes bibliographical references (leaves 102-104).

Thesis (M.S.)--University of Arizona. / Includes bibliographical references.

Thesis (M. S. - Soil, Water and Environmental Science)--University of Arizona, 2003. / Includes bibliographical references (leaves 159-170).

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1968. / Includes bibliographical references (leaves 48-51).