| Catastrophic failures of tailings impoundments, in which liquefied tailings flow over substantial distances, pose severe hazards to the health and safety of people in downstream areas, and have a potential for economic and environmental devastation.; The purpose of this study, an extension of prior investigations, was to develop procedures to measure Bingham flow parameters for mine tailings. In addition, the analytical procedures developed by Lucia (1981) and Jeyapalan (1980) for predicting the consequences of tailings flow failures were evaluated and applied to the Tenmile Tailings Pond at Climax, Colorado.; Values of the dimensionless parameters (tau)(,y) (the Bingham yield shear strength) and (eta)(,p) (plastic viscosity) were determined for 10 materials using results obtained from a vaned coaxial viscometer developed during this study, and the results of traixial test results performed by Castro (1982). Values of (tau)(,y)/(sigma)(,1)' ((sigma)(,1)' = consolidation pressure) ranged from 0.05 to 1.0 and values of (eta)(,p)(.)(gamma)(,0)/(tau)(,y) ((gamma)(,0) = 1 radian/sec) ranged from 0.002 to 0.04. No strong correlation between these values and index properties could be established.; Procedures for estimating in-situ values of (tau)(,y) and (eta)(,p) were based on a consolidation theory developed by Gibson (1958) and a compter program (CONSOL).; Revisions in the simplified equilibrium procedure, developed by Lucia (1981), make it more compatible with infinite slope solutions. A correlation between an apparent residual strength, S(,ur) and impoundment height was established based on back-calculated values. There is a fundamental difference between S(,ur) and (tau)(,y); S(,ur) includes the static resistance ((tau)(,y)), the viscous resistance ((eta)(,p) (gamma)), and inertial effects.; Jeyapalan's model was evaluated using a simple rheological analogy, and it appears there are some numerical difficulties with the operation of the computer program TFLOW used to model the displacements and velocities of flow slides.; Comparable flow distances can be determined using either model if the flow volume used in the simplified equilibrium procedure is estimated properly.; When both analytical procedures were applied to the Tenmile Pond, it was concluded there was no potential for a flow slide at the site due to the high value of (tau)(,y)/(sigma)(,1)' relative to the existing slopes. |
