Centrifuge Modeling of Coal Waste Embankments

Centrifuge model embankments with varying geometries and properties were constructed of coal waste material, accelerated to 100-120, and subjected to various reservoir depths until failure occurred. Complimentary laboratory tests were performed on the waste materials to obtain strength and permeability parameters for analytical calculations to predict observed centrifugal model behavior. Failures occurred in model embankments with 1 Vertical:1.5 Horizontal and 1 Vertical:2 Horizontal slopes when the phreatic surface due to seepage exited on the downstream slope and initiated sloughing at the toe. Positive seepage control, i.e., a toe drain, successfully prevented sloughing and failures. Slope stability analyses agreed well, albeit conservatively, with observed model performance. These models verified existing criteria of minimum safety factor of 1.3 and the necessity of positive seepage control.