This paper predicts the possibility of water inrush from a confined aquifer under the action of mining activities and water pressure. The study uses numerical analyses to evaluate stress redistribution and crack growth which result from coal extraction operations. Two models are presented in this study. By simplifying the distribution of the disturbed vertical stress on the coal seam and floor around a working face, a model is established to analyze the additional stresses in the floor strata induced by mining activities. And some distribution features of all the additional stress components are described. By using the superposition principle in fracture mechanics, another model is developed to analyze the crack growth in the floor strata under the action of disturbed stresses and water pressure. And the stress intensity factors at the crack tip are presented and the process of crack growth is obtained in the advancement of a working face. Because of discretizing only loading areas and crack surfaces, the present methods can obtain the accurate numerical results. Finally, some suggestions are made for preventing the water inrush from a confined aquifer.

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The paper examines the elastic fields of displacements and stresses for a nonhomogeneous elastic half-space where the elastic parameters have a linear variation over a finite depth beyond which it is constant. The circular loading area is subjected to a uniform inclined load. The numerical method is developed by applying the fundamental solution of a layered elastic solid and integrating numerically it over the loading area. As a result, only the loading area needs to be discretized in using the proposed numerical method. Numerical examples of calculation of displacements are conducted, and excellent agreement with the existing closed-form solutions is obtained. The results obtained are used to understand the elastic fields induced by different types of loads in a nonhomogeneous medium.