The Evolution and Prevention of Water Inrush Due to Fault Activation at Working Face No. II 632 in the Hengyuan Coal Mine

The water-bearing capacity and abnormal water-bearing area of the coal seam floor of working face no. II 632 at the Hengyuan coal mine was investigated using the network parallel electrical method. Based on the limit equilibrium theory and Mohr–Coulomb yield criterion, we obtained a critical water pressure formula. Using fault DF137 as an example, we found that the abnormal water-bearing phenomena around the working face was related to nearby faults and that the water inrush was mainly due to faults being activated during mining. The pathway of water inrush under the coupled effects of stress induced by mining and the confined water pressure was modelled in Flac3D based on the fluid structure interaction (FSI) method. Considering the economics and operational convenience, grouting the working face floor was recommended to prevent an inrush. Based on a geophysical evaluation, the grouting effectively prevented a potential inrush.