Tectonic setting and risk zoning of dynamic geological disasters in coal mines in China

Coal and gas outburst,mine water inrush,rock burst,roof fall and other dynamic geological disasters in coal mines have seriously threatened the coal mining safety. Further research on the formation mechanism and distribution law of mining dynamic geological disasters is the precondition and basic work to ensure the safe production of coal mine. The formation of dynamic geological disasters in coal mines is the result of coupling action of the static geological environment and the mining disturbance. The regional tectonic setting determines the occurrence feature and dynamic environment of coal deposits by means of the structural deformation products,the structural formation process and the tectonic stress field,and result in the risk of dynamic geological disasters. Based on the cases study and theoretical analysis,the disaster-causing structure factors can be summarized into six types:faults,folds,structural complexity, tectonic activity,coal deformation-metamorphism,coal seam buried depth,etc. ,and the different types of structural factors have different effects on different geological disasters. Controlled by the coalfield tectonic framework,the inten- sity of mining dynamic geological disasters increases from west to east and from south to north in China. The large- scale and serious-damaged disasters mainly occur in the eastern coalfield tectonic domain,especially to the east of the secondary-order structure belt of Daxinganling Mountain-Taihang Mountain,in the east-central part of Northeast China coal occurrence structural areas,the east part of North China coal occurrence structural areas and the central part of South China coal occurrence structural areas,and the western part of South China coal occurrence structural areas which is controlled by the Tethys geodynamics system and the Pacific geodynamics system. According to the character- istics of disaster-causing structure factors and dynamic geological disasters,and combined with the coal measures oc- currence and coal mining status,the mining dynamic geological disasters controlled by regional tectonic setting can be divided into three risk grades:grade I ( low risk),grade II ( medium risk) and grade III ( high risk). Based on the space-time difference of China’s coalfield tectonics,the risk zone division of main dynamic geological disasters in coal mines is carried out within the framework of coal occurrence structural units in China,there are 11 zones of grade Ⅲ and seven zones of grade Ⅱ in four major coal occurrence structural areas of Northeast China,North China,South Chi- na and Northwest China,the rest belong to grade I zones or unevaluated areas.