Thesis (M.S.)--Brigham Young University. Dept. of Civil and Environmental Engineering, 2007. / Includes bibliographical references (p. 99-100).

Thesis (M.P.A.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves i-v). Also available in print.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (p. 379-394). Also available in electronic version.

The design characteristics of an active waste disposal capsule placed within a saturated groundwater environment is investigated, with the objective of developing a methodology to determine environmentally, technically and economically feasible conditions for its operation. In operation, conditions are created and maintained within and surrounding a containment cell to insure that a potential for convective inflow exists everywhere across an encapsulating barrier which tends to counter the potential for outward dispersion through the barrier. A computer algorithm based on the finite element method has been developed in the BASIC language to aid in the hydraulic analysis. Essentially, it provides a numerical solution to potential flow through porous media for two dimensional anisotropic solution domains of various materials. Data generated from this algorithm for cases of varying geometric material and boundary properties are used to verify and quantify assumed relationships involving critical design parameters which have been developed through dimensional analysis and physical reasoning. An expression describing the concentration profiles developed across the barrier is obtained by solving the one-dimensional convection-dispersion equation for steady conditions within and bounding the capsule barrier. Applying this result to an identified critical point allows conservative barrier design criteria to be developed so that operation of the active capsule results in only negligibly small amounts of contamination escaping through the barrier to the environment. By introducing cost coefficients which are descriptive of various aspects of construction, operation and maintenance of the active capsule, a total cost function is formulated from which, when minimized with respect to various design variables, optimizing criteria are developed. Finally, a predictor-corrector optimization program which incorporates the results of this study is developed and used to investigate an illustrative problem. / M.S.

The objective of this study was to investigate the accuracy of the procedures employed in the conventional equilibrium method of analysis of gravity-earth-retaining structures founded on rock, using the finite element method of analysis. This study was initiated because a number of existing large retaining structures at various navigation lock sites in the United States that show no signs of instability or substandard performance have been found not to meet the criteria currently used for design of new structures. The results of following load analyses show that when the loss of contact along the base of a wall is modeled in the finite element analysis, the calculated values of effective base contact area and maximum contact pressure are somewhat larger than those calculated using conventional equilibrium analyses. The values of the mobilized base friction angle calculated using both methods are in precise agreement. Comparisons between the results of backfill placement analyses using the finite element method and the conventional equilibrium analyses indicate that conventional analyses are very conservative. The finite element analyses indicate that the backfill exerts downward shear loads on the backs of retaining walls. These shear forces have a very important stabilizing effect on the walls. Expressed in terms of a vertical shear stress coefficient (Kᵥ - r_xy/σᵥ), this shear loading was found to range in value from 0.09 to 0.21, depending on the geometrical features and the values of the material parameters involved in the problem. Another important factor not considered in the conventional equilibrium method is that the displacements of the wall have a significant influence on the distribution of both the stabilizing and destabilizing forces exerted on the wall. In general, as the wall moves away from the backfill, the lateral forces exerted on the wall by the backfill decrease, and the lateral forces exerted on the front of the wall by the toe fill increase. / Ph. D.

Virginia is rapidly running out of landfill space. Recycling is seen as a way to alleviate some of the burden on our landfills. The Commonwealth of Virginia has mandated an ambitious recycling goal of 10% of our municipal solid waste (MSW) by 1991, 15% by 1993, and 25% by 1995. Yardwaste (debris such as leaves, grass clippings and shrub and tree prunings) comprises an estimated 15% to 20% of the municipal solid waste going into our landfills daily. Yardwaste can be recycled by collecting the material, piling it into large windrows, and allowing it to decompose by a controlled process called composting. The finished product can then be utilized as a soil amendment for use by nurseries, landscapers, farmers, local and state government landscaping projects, and by homeowners. The Virginia Cooperative Extension Service at Virginia Tech was authorized to perform a study on the feasibility of implementing a statewide yardwaste composting program for Virginia. The methods involved in the study included information acquisition via a literature review, site visits in other states to assess technologies and a series of surveys to determine potential uses and users of composted yardwaste in Virginia. The feasibility study was presented to the Virginia Department of Waste Management in November 1989 and presented as House Document No. 34 to the 1990 Session of the Virginia General Assembly. Several pieces of legislation, including three bills and one joint resolution, are currently pending concerning the results of the study. / Master of Science

published_or_final_version / Architecture / Master / Master of Landscape Architecture

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements of the degree of Master of Science in Geology Johannesburg, 1998 / This study determines the potential of prerncting pollution to ground water by sanitary landfills. The tracing capabilities of both stable and radioactive environmental isotopes are also evaluated. Four landfills were selected, the Linbro Park and Waterval sites in Johannesburg, and the Bloemfontein northern and southern landfill sites. The sites all differ in geological environment, size. age and physiographic setting. [Abbreviated Abstract. Open document to view full version] / MT2017

Earthwork operations are often one of the major cost items on infrastructure construction projects. Because earthwork is largely influenced by unstable construction conditions and organization plans, it becomes the emphasis and difficulties of the cost control in the construction process. Therefore, precise estimates of actual earthwork volumes are important for both owners and contractors alike to ensure appropriate payments are made. However, measuring work on site requires lots of time and labors because of various and irregular site conditions. Conventional measurement methods, such as planned quantities from the drawings or estimates from equipment activity, are rough estimates with significant opportunities for errors and safety concerns. Recently, unmanned aerial systems (UAS) have become popular for numerous surveying applications in civil engineering. They require less cost and time consumptions compared with traditionally manual methods. Also, they are able to perform photogrammetric data acquisition with equipped digital cameras in hazardous, complex or other conditions that may present high safety risks. However, UAS photogrammetry for research applications is still in its infancy, especially in construction management, and research conducted on UAS photogrammetry for earthwork volume estimation are very limited. Therefore, this research intends to investigate and validate the feasibility and efficiency of utilizing the UAS photogrammetry surveying technique to estimate earthwork volume. The research is conducted into three steps based on distinct case studies: firstly, adapting a basic analysis through a case study to preliminarily prove the effectiveness of the UAS photogrammetry method in earthwork volume measurement; also providing an analytical foundation for further utilizations; secondly, Quantitatively assessing the impact of flight parameters and environmental factors on the accuracy of UAS photogrammetry in earthwork volume measurement and identifying the most influential individual or combinations through observations and a statistical multiple regression analysis; at last, comparing volumes calculated by using the UAS platform and other two conventional methods which are Average-End-Area method and grid method in AutoCAD to further validate the feasibility of using the UAS technology in the process of earthwork volumes estimation. The results indicate that the UAS is an effective method for earthwork volume measurement. According to published standards, practice experience, and literature, the measurement errors are in an acceptable range when parameters are under control. In addition, the UAS demonstrates its advantages in balancing between the accuracy and efficiency compared with conventional earthwork volume measurement methods.