Investigating the effects of rainfall and groundwater on coal mine waste dump stability: a case study


Affiliations

  • National Institute of Technology, Research Scholar, Department of Mining Engineering, Raipur, India
  • National Institute of Technology, Assistant Professor, Department of Mining Engineering, Raipur, India
  • National Institute of Technology, Assistant Professor, and Prof. Department of Mining Engineering, Raipur, India

Abstract

Sudden inrush of rainwater in the waste dump as well as the saturation of the dump material in case it is constructed near the source of water, increases the risk of dump failures due to water infiltration through the dump. A number of dump failures have been reported in the past during monsoon season. Understanding the hydrogeology of the project area and prospective sites should be required to be considered while designing and constructing the dumps. High groundwater levels and pore pressures in the dump foundation adversely affect the static dump stability. Construction of waste dump changes the natural ground levels and flow regime. Water induced failure like ponding of surface should be avoided, particularly adjacent to dump crests by drainage ponding. In this present study, the rainfall-induced waste dump profile of the Srirampur opencast project is addressed by understanding its climatic and hydrogeological conditions. An infiltration analysis of single event rainfall conditions was performed with a focus on cumulative rainfall calculations. Instability calculations need consideration for the seepage force which is an internal force when the soil grains alone and soil skeleton plus the water are considered for the free body. For this purpose, under the steady-state time-dependent flow, an analysis on the influence of single event rainfall was built from the rainfall data to know the parameters for infiltration and seepage conditions. Stability calculations were performed in FLAC2D for any uplift force exertion on the bottom of the coal waste dump in the operating mining conditions.

Keywords

Waste dump, dump stability, rainfall, groundwater, infiltration, saturation, pore pressure

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