Numerical Simulation On Mechanical Characteristics Of Surrounding Rock In Rock Cross-cut

The mechanical characteristics of surrounding rock in rock cross-cut have challenged many researchers from engineering mechanics and materials science to devote them to it. Coal and gas outbursts followed by the failure and fracture of gaseous coal and rock have been the major disasters in the world mining industry and it has occurred in virtually all the major coal producing countries of the world. The disastrous mine outburst has resulted in great loss of life in many countries and even today it is not well understood. Thus, as a theoretical foundation of the mechanisms of coal and gas outbursts, this has forced mining leaders and researchers to develop an understanding of the mechanical characteristics of surrounding rock in rock cross-cut, and the mechanisms of coal and gas outbursts and gas drainage, and furthermore, to adopt some safety procedures to minimize the effect of outbursts or eliminate them completely. Therefore, it is of great importance and significance to investigate the mechanical characteristics of surrounding rock in rock cross-cut under various conditions.Laboratorial tests and in-situ observations have been an effective and direct ways of studying the failure process of gaseous coal and rock, and these ways play a crucial role in the study of material failure process. Nevertheless, the applications of these methods in the study of gaseous coal and rock are limited because of safety. Analytical method such as mathematics and engineering mechanics is also important in investigating the stress-strain relation and the induced acoustic emission some simplifications to materials. However, the mathematical and mechanical methods are seemed to be weak in dealing with the complex inter actions among micro-cracks and the coupling inter action between gas flow and coal or rock deformation. As a result, numerical method, a most widely used and effective method, can serve as a tool to study the mechanical characteristics of surrounding rock in rock cross-cut. Based on the microscopic structures and constitutive relation of coal and rock on a meso-level, the mechanical characteristics of surrounding rock in rock cross-cut can be solved combined with computational mechanics and statistics. The combinations of damage mechanics and coal methane seepage mechanics make it possible to numerically simulate the gas flow in the failure process of coal and rock. In addition, the quick development of computer hard ware and computational mechanics make it a powerful tool to investigate the mechanical characteristics of surrounding rock in rock cross-cut on a meso-level.Therefore, in the present paper, firstly, three plastic damage constitutive law for element on a meso-level was proposed considering the heterogeneity of coal and rock, mean while, considering the relationship equation between damage induced gas permeability and stress and time-dependent equation of creep damage evolution, the solid-gas coupling model (RFPA^2D-Flow) for gaseous coal and rock was established, and the numerical FEM implementation for the model was also given. Further more, the coupled model was also validated from two aspects of the mechanical characteristics of surrounding rock in rock cross-cut.,Secondly, the instantaneous outburst induced by cross-cut driving is numerically performed, respectively. Numerical results reproduced the whole process of micro-cracking, propagation, coalescence and ejection of coal or rock. In addition, the associated stress fields, displacement vectors, audio energy and flow volume during the outbursts clearly visualized.Thirdly, study the conditions of the outbursts of coal and gas pertinently. Keeping other parameters value invariable, changing the gas pressure in coal seam only, the author simulates the outbursts of coal and gas in cross-cut. The result indicated that reducing the gas pressure in the coal seam is an efficient way to forbide coal and gas outburst.