The displacement and deformations of rock mass due to underground mining has often resulted in major disasters throughout the world, Frequently inflicting heavy losses of life and damage to property. And these disasters have motivated the development of rock mass mechanics. The prediction of displacement of rock mass and their surface effects is an important problem of the rock mass mechanics ill the excavation activities especially the coal and metal mining in mountainous areas. Based oil results of the statistical analysis of a large amount of measured data in mining engineering, the fundamental fuzzy model of displacements and deformations of rock mass is established by using the theory of fuzzy probability measures. The theories of both two- and three-dimensional problems are developed and applied to the analysis of engineering problems in excavation and underground mining ill Mountainous 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 displacements and deformations and the safety evaluation of the buildings on the ground. (c) 2005 Elsevier Ltd. All rights reserved.