Stochastic Modelling of the Hydraulic Anisotropy of Ash Impoundment Sediment

[摘要] In the case reported here the impoundments of a 400 MW coal heated power plant with an annual production of about 1.5 million tons of fuel ash are of the cross-valley type, operated by the simple and cheap upstream method". The aim of the research was to determine overall and local values of the permeability in horizontal as well as in vertical direction and the anisotropy of the thin-layered sedimented ash. The coal ashes are hydraulically transported through pipelines in form of a slurry and periodically floated on the beach of the impoundment. The ashes are deposited in the form of a thin-layered sediment, with random alternation of layers with a coarser or finer granularity. The ash impoundment sediment is anthropogenic sediment with horizontally laminated texture. Therefore, the sediment is anisotropic from the viewpoint of water seepage. The knowledge of the permeability and the seepage anisotropy of the sediment is a basic requirement for the design of an appropriate dewatering system. The seepage anisotropy of the ash sediment has been checked by means of stochastic modelling, based on the correlation between the effective grain diameter and the coefficient of permeability of the ash: the effective grain diameter and the thickness of individual layers have been proposed to be random events.

[发布机构] Slovak University of Technology, Faculty of Civil Engineering, Department of Geotechnics, Radlinského 11, Bratislava; 810 05, Slovakia^1

[关键词] Annual production;Coefficient of permeability;Dewatering systems;Fuel ash;Grain diameter;Hydraulic anisotropy;Vertical direction;Water seepage