Browsing by Author "Doehring, Donald O., committee member"

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Open Access
Development of the piezovane for estimating liquefaction potential of saturated sands
(Colorado State University. Libraries, 1994) Butler, Leo Wm., author; Charlie, Wayne A., advisor; Siller, Thomas J., committee member; Doehring, Donald O., committee member
The Piezovane was developed for determining in situ liquefaction potential of saturated sands by measuring the porewater pressure response oi saturated sand during and after shearing of the soil. A negative porewater pressure response is an indication that the material is in a dense (dilative) state; therefore is not susceptible to liquefaction failure. Positive porewater pressure response is an indication that the sand is in a loose (contractive) state and is susceptible to liquefaction-type failure. This project included design, fabrication of the Piezovane apparatus and the calibration chamber for the initial laboratory testing. Sands were placed within the calibration chamber at densities greater than or less than densities at the steady state which had been developed by using CU triaxial and CD direct shear tests. Trends indicate that the Piezovane testing can predict contractive or dilative behavior of soils. Additional testing both in the laboratory and in the field is required to determine whether these measured porewater pressure responses and measured shear resistances provide parameters needed for evaluating liquefaction potential and their possible use for design. A patent for the Piezovane has been awarded.
Open Access
Known discharge uncoupled sediment routing
(Colorado State University. Libraries, 1982) Brown, Glenn O. (Glenn Owen), author; Simons, Daryl B., advisor; Li, Ruh-Ming, advisor; Doehring, Donald O., committee member
A known discharge, uncoupled, sediment routing model, KUWASER has been developed. The model sequentially solves the steady flow and sediment continuity equations. This procedure allows for efficient solution of sediment routing problems on large river systems. The model can perform backwater calculations and sediment routing in main stem and multiple tributaries including divided flow reaches. The user can determine river response to river management practices such as channel improvement, realignment, dredging or tributary modifications. The model was tested against two other models, a stage-discharge relationship and a fixed bed model by comparing the frequency of model errors in stage prediction. A sensitivity analysis was performed to determine the sensitivity of the models results to variations in six input parameters. The Yazoo River Basin in Mississippi was used as a case study to demonstrate the model capabilities. The model can be an effective tool in the prediction of river response.
Open Access
Time and scale effects in laboratory permeability testing of compacted clay soil
(Colorado State University. Libraries, 1989) Javed, Farhat, author; Shackelford, Charles D., advisor; Jameson, Donald A., advisor; Doehring, Donald O., committee member; Abt, Steven R., committee member
Permeability (hydraulic conductivity) testing of clays in the laboratory typically requires a significant amount of time. It is hypothesized that the time required for clay permeability test can be reduced substantially through a statistical modelling technique known as "time series analysis". In order to test this hypothesis, permeability tests were performed on compacted samples of a silty clay soil in a standard Proctor mold (9.4 x 10-4 m3). The soil was separated into five different fractions representing five ranges in precompaction clod sizes. Constant-head permeability tests were performed on each of these five fractions. Tests were replicated five times for the time series analysis. The results of analysis indicate that time series modelling can significantly reduce statistical error associated with permeability data. It is demonstrated that the time required for clay permeability test can be reduced appreciably through time series modelling. Permeability tests also were performed on four soil fractions in a large-scale (0.914 m x 0.914 m x 0.457 m) double-ring, rigid-wall permeameter. The results of small-scale (Proctor mold) permeability tests indicate that the soil permeability does not vary much with a change in the precompaction clod size. Presence of large clods (> 25 mm), however, may result in side-wall leakage. The large-scale tests indicated that permeability is strongly related to the precompaction clod sizes. Permeability of the soil increased more than two orders-of-magnitude as the maximum precompaction clod size increased from 4.75 mm to 75 mm. Comparison of the results from the small-scale and the large-scale tests indicated that, for all soil fractions, the large-scale permeability was higher by more than an order-of-magnitude. As a result, there appears to be a scale-effect associated with laboratory permeability testing. This scale effect is more significant when soil contains considerable quantity of clods that are large relative to the size of permeameter. These results imply that the large-scale test is more capable of accounting for the hydraulic defects resulting from large clods. A more realistic evaluation of the field permeability of a compacted clay, therefore, may be possible in the laboratory if the permeameter is fairly large relative to the maximum precompaction size of clods present under field conditions.
Open Access
Watershed management concerns in general plan formulation for regional governments
(Colorado State University. Libraries, 1982) Diederich, William Dean, author; Held, R. Burnell, advisor; Dyer, Archie A., committee member; Doehring, Donald O., committee member
Most city, county, and regional planners are more comfortable with discussing urban/suburban related issues than natural resource issues. The reason is due to the education planners receive. Eventually, counties and regions, and cities with large open areas, will have to plan for the managed production of all resources as they become scarcer. This paper addresses the watershed basin as an area that should be managed for its most important product: water. The paper attempts to show the planner the basics of watershed management, methods to include watershed management in general plans, and concepts of water law that affect ownership of watershed water. Discussion departs from the traditional approach of watershed management planning for regional economic development and soil erosion control to focus on the watershed as a resource producer.