Design of embankment for safe back filling in opencast mines: A case study

摘要

Disposal of coal ash generated by thermal power plants is a challenge now days under rigid environmental norms. The conventional method of disposing in ash ponds leads to requirement of huge amount of valuable land and it have adverse effect on air, ground water and soil. Hence, the need of the hour is to utilize this ash in an environment friendly manner. In this paper a technical option for safe back filling practices by constructing embankment in the de-coaled area is discussed. This paper throws a light on the scheme for utilizing coal ash in combination with overburden (O/B) material as a filling material in abandoned portion of the mine. The filling work is carried out by design of embankment to contain it against the high wall. Out of several methods of embankment construction, downstream method of embankment method is used. To design embankment safely numerical simulation was carried out by using PLAXIS-3D which is based on Finite Element Method. The construction scheme involves raising of embankment with slope angle of 270in eight stages of ten meters height each and simultaneously filling it with high concentration ash in layers. The material used for embankment construction was coal ash and OB. In the final stage, the top soil of 5m thick is proposed to be spread for re-vegetation.