Papers by Clifford Anderson
This study uses data collected at two National Summer Transportation Institute (NSTI) programs in... more This study uses data collected at two National Summer Transportation Institute (NSTI) programs in Connecticut and Mississippi to investigate high school students’ perceptions and preferences about education in science, technology, engineering and mathematics (STEM). Family background has a significant impact on a high school student's interest in STEM, as shown during the student recruitment stage and by the analysis of the students' college education plans prepared upon graduation from the two NSTI programs. The building exercise and competition instrument is the most effective among the few examined, while passive learning is not what young people prefer when briefly introduced in the two NSTI programs.
Scour and Erosion, 2010
In arid climates the steep side slopes of a landfill can be sources of severe erosion. The amount... more In arid climates the steep side slopes of a landfill can be sources of severe erosion. The amount of vegetation that can be sustained commonly does not provide significant erosion protection, and alternative erosion protection measures are required. The commonly used side slope terrace drains can be difficult to construct and maintain. A method is presented to compute the gradation and thickness of a rock surface erosion protection layer that will allow for longer slope lengths than has been commonly applied. The procedure considers peak flow, slope and the formation of surface channelization. Criteria for applying a granular filter are also considered. As an alternative to separately placed riprap and granular filter layers, a combined mixture could serve the same function as separate layers, and reduce construction costs. A gradation range is considered for a combined mixture, and a series of gradations within the range is examined to determine the critical layer thickness. Examples of a resulting side slope design are presented.
Scour and Erosion, 2010
Surface water can enter landfill waste zones from top surface areas and erosion of the top surfac... more Surface water can enter landfill waste zones from top surface areas and erosion of the top surface can cause wash-out of waste material. Landfill covers at these locations must prevent surface water infiltration and provide erosion resistance. In arid climates a rock veneer can be used to reduce erosion, but this will increase infiltration and reduce surface evaporation making it more likely that surface water will enter waste zones. An alternative is the placement of a mix of soil and gravel as a surface layer; the mix is commonly called a gravel admixture. Studies of gravel admixture layers have shown they provide greatly reduced surface infiltration rates over gravel alone, and have evaporation rates very similar to soil alone. A method is presented to compute the rock and soil gradations, and thicknesses of gravel admixture layers based on peak flow , slope and the formation of surface channelization. The procedure is used to select gradation ranges and applicable slope lengths for a landfill cover.
Capillary Barrier Effect from Underlying Coarser Soil Layer
Journal of Geotechnical and Geoenvironmental Engineering, 1999
Infiltration tests were conducted on soil columns of silty sand over pea gravel, concrete sand ov... more Infiltration tests were conducted on soil columns of silty sand over pea gravel, concrete sand over pea gravel, and silty sand over concrete sand to investigate the capillary barrier effect of an underlying coarser soil layer. Water movement across the interface occurred when the suction head at the interface reached the breakthrough head of the coarser lower soil layer, defined as the suction head at which the coarser layer first became conductive, regardless of infiltration rate or the properties of the overlying finer soil layer. Thus, the coarser lower soil layer controlled breakthrough in this study. After infiltration was terminated, the suction head near the interface increased above the breakthrough head and the barrier was restored. The breakthrough head did not change substantially after eight test cycles of breakthrough and restoration for a capillary barrier with a pea gravel as the coarser lower soil layer. The barrier formed with the concrete sand as the coarser layer permitted breakthrough at a greater suction head than did the barrier with the pea gravel, indicating that the more uniform and coarse the lower soil layer is, the more effective the capillary barrier.
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Papers by Clifford Anderson