Internal waste dump stability analysis: insights from numerical simulations

In Mongolia, the “Baganuur” lignite coal mine is one of the largest open-pit mines; however, the stability of its internal dump is very difficult to maintain, which hinders the mine’s normal operation and negatively influences the economy. To solve this internal waste dump slope stability problem, we studied the use of rock materials’ inherent mechanical properties to conduct numerical modelling and analysis on improved internal waste dump parameters using Gaussian Elimination-based Rocscience RS2 software. Finite element methods were used to determine the factors that could impact the stability of an internal waste dump based on the properties of the rock. For this research, we investigated whether single- and multi-dumps impacted internal dump height and dip angle and covered the analytical approach used to determine safety factors. The internal dump capacity can be increased by around 1.9 times at a 50 m height and a 28° dip angle, according to the results of the numerical simulation models. This research offers an optimal strength reduction factor (SRF) at a height of 45 m and a dip angle of 28° in comparable situations. Numerical simulations show that dip angle changes impact internal dump slope stability more than dump height modifications.