Landslide and subsidence in waste dump is a major problem which most mining industry countries is facing, Viet Nam is not an exception. To reduce the effects of disasters such as subsidence, there have had many developed subsidence prediction methods. In this paper, prediction function of Knothe was presented. Based on Knothe function, the authors built a subsidence prediction module and applied it for Nam Deo Nai waste dump, Quang Ninh, Viet Nam. The predicted values from this module was compared to the actually measured data, the smallest difference of subsidence is -0.003 m, equivalent to 5.3%, the largest difference is 0.011 m, equivalent to 4.3%. The small disparity between the largest and smallest difference shows the result has a high convergence. As the final result, it is found that the developed module is powerful and effective tool for waste rock dumps subsidence prediction.
Many waste rock dumps can be considered as a potential source of environmental problems, such as subsidence, erosion and landslide, which lead to significantly negative impacts on surrounding areas where have many civil works as house, school, etc (Fig. 1a). There have been many serious incidences due to landslide at waste dumps of Vietnam National Coal – Mineral Industries Holding Corporation Limited (Vinacomin). For example, ten houses were buried due to the landslide occurring at the rock waste dump of Phan Me coal mine (Thai Nguyen Iron and Steel Joint stock Corporation) in early morning 15/4/2013 (Fig. 1b) (Vnexpress.net, 2013). Vinacomin has taken many solutions in order to increase the stability of waste dumps, such as dumping by benches, dumping by surface, building the system of walls at the food of waste dump and planting trees, etc. However, it is necessary that waste dumps are monitored frequently and then the warnings of environmental hazards are informed earlier. Therefore, many monitoring works have been built in large waste dumps by mining companies owned by Vinacomin.