published_or_final_version / Applied Geosciences / Master / Master of Science

The LMVD Method of Planes has been used for many years by the New Orleans District of the U.S. Army Corps of Engineers to analyze the stability of flood control structures in the New Orleans hurricane protections system. The Method of Planes assumes a three-part, noncircular slip surface and generally does not satisfy any form of static equilibrium. In computing a factor of safety, the Method of Planes considers a balance of horizontal “resisting” and “driving” forces in computing a factor of safety. To better understand how the results of slope stability analyses with the Method of Planes compare with results from more rigorous procedures capable of analyzing slip surfaces with different shapes, a parametric study was performed by analyzing twenty earthen levee cross sections believed to represent the various levee configurations in southeastern Louisiana. Analyses were performed with a force equilibrium procedure that assumed a horizontal inclination for the interslice forces and Spencer’s (1967) procedure, and the results were compared with the solutions from the Method of Planes. The force equilibrium procedure with horizontal side forces was selected because the procedure is believed to yield results that are similar to results from the Method of Planes, and Spencer’s procedure was utilized because it is the only procedure considered in this study to completely satisfy static equilibrium. The analyses performed with the force equilibrium and Spencer’s procedures included analyses for the critical slip surfaces from the Method of Planes as well as analyses for critical circular and noncircular slip surfaces. It was shown with the results of the analyses that the shape of the assumed slip surface has a great effect on the differences in the factors of safety from Spencer’s procedure and the Method of Planes. / text

Slope stability problems often arise in construction engineering projects. They are major problems in dams construction and mines excavation. For the purpose of improving the efficiency of slope stability analysis, the optimization method suggested by Powell (1964) is used to locate the critical failure surface. The reader should bear in mind the possibility of applying optimization to a wide variety of different civil engineering problems.

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Erosion on the slopes of mine tailings represents one of the most important environmental problems arising from the disposal of mine tailings. Tailings dam erosion is the main source of pollution that contaminates agricultural land and streams around mining areas. There is an urgent need to reduce erosion of the slopes of mine tailings in-order to limit further devastation of natural ecology. The present study investigates the possible use of cement to reduce erosion of the slopes of mine tailings dams. The pinhole erosion test was used to measure erodibility of tailings stabilized with cement. The strength properties of cement-stabilized tailings have been evaluated by the unconfined compression test. Conbex and ordinary Portland cement have been used for tailings stabilization, with contents of 0, 3, 5, 7, and 10% by mass. It has been established that cement can be used to reduce erosion of the slopes of mine tailings dams. At least 3% by mass cement is required to produce zero erosion loss. The resistance of tailings to erosion can be enhanced by increasing compaction density, curing period and cement content. Ordinary Portland cement produced higher strengths and erosion resistance than Conbex, although Conbex may be useful for stabilizing fine tailings. Cement-stabilized tailings could be used to make bricks and rubble for use in reducing erosion of the slopes of mine tailings dams. As little as 10% of cement is necessary to produce unconfined compressive strengths of 1600- 2600 kPa.

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Thesis (M. Sc.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references. Also available in electronic version.