Prediction of Surface Subsidence Extension due to Underground Caving: A Case Study of Hemushan Iron Mine in China

Figure 2

Laubscher’s empirical model for predicting the angle of break as a function of the mining rock mass rating (MRMR) and the factor (F) calculated from the parameters of the caved materials and undercut; the MRMR will recognize the stress effects and whether the joints are clamped on the minimum span or in extension on the maximum span side; (F) can be calculated by , where is the density of the cave materials; is the height of the caved materials; is the depth of the undercut; and is the minimum span of the undercut (after Laubscher [8]).