The prediction of rock mass displacement and their surface effects is an important problem of the rock mass mechanics in the excavation activities especially the metal and nonmetal mining in mountain areas. Based on results of the statistical analysis of a large amount of measured data in mining engineering

the fundamental theoretical model of ground surface movements due to underground mining is established by using the theory of probability. The formulas of rock mass displacements and deformations are developed and applied to the prediction of the ground surface movements due to underground mining in Yi-chang mining areas. The agreement of the theoretical results with the field measurements shows that our model is satisfactory and the formulae obtained are valid and thus can be effectively used for predicting the movements and the natural slope failure due to underground mining of phosphorus ore-deposit in mountain areas.