A model for estimating the hydraulic conductivity of granular material based on grain shape, grain size, and porosity
- Duke Univ., Durham, NC (United States). Dept. of Civil and Environmental Engineering
Particle shape is an important parameter in numerous civil, environmental, and petroleum engineering applications. In ground-water flow, the shape of individual particles comprising the soil affects the soil`s pore size distribution and, hence, the important flow characteristics such as hydraulic conductivity and headloss. A model for delineating the relative importance of particle size, particle shape, and porosity, (and their interactions), in explaining the variability of hydraulic conductivity of a granular porous medium is developed and tested. Three types of porous media are considered in this work: spherical glass beads; granular sand; and irregularly shaped, shredded glass particles. A reliable method for quantifying the three-dimensional shape and packing of large samples of irregular particles based on their angle of repose is presented. The results of column experiments indicate that in the size range examined (i.e., 149 {micro}m to 2,380 {micro}m), the single most important predictor of hydraulic conductivity is seen to be particle size, explaining 69% of the variability. Porous media comprising irregular particles exhibit lower hydraulic conductivity only for the larger (707 to 841 {micro}m) particles. For the smaller (149 to 177 {micro}m) particles, particle shape has no observable influence on hydraulic conductivity. The results of the regression analysis reveal the importance off the interaction between particle size and porosity, indicating that similar pore configurations for a given type of particle are not achieved at different sizes. This empirical model seems to provide better estimates of the hydraulic conductivity of granular porous media comprising irregular particles than selected models based solely on grain size, including Hazen, Kozeny-Carman, and more recently Alyamani and Sen.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 128857
- Journal Information:
- Ground Water, Vol. 33, Issue 6; Other Information: PBD: Nov-Dec 1995
- Country of Publication:
- United States
- Language:
- English
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