Fault activation caused by construction, earthquakes, or mining can produce disastrous water-inrush episodes in underground mines. Fault activation is generally caused by stress concentration at the fault tip, so in this study, a computational model of a typical underground stope with a hidden fault was established to quantitatively assess the magnitude of the stress concentration of the stress fields of the fault-tip. Numerical simulation was performed using the extended finite element method and fracture mechanics. Stress intensity factors, which represent the magnitude of the stress concentration, were obtained using the interaction integral method to quantitatively evaluate the tip fields and assess the possibility of fault activation. The mining depth, fluid pressure, fault dip, and fault length were analyzed and the advance of a working face was simulated to determine whether underground mining would cause fault activation.

Sudden water inrush has been a deadly killer in underground engineering for decades. Currently, especially in developing countries, frequent water inrush accidents still kill a large number of miners every year. In this study, an approach for predicting the probability of fault-induced water inrush in underground engineering using the adaptive neuro-fuzzy inference system (ANFIS) was developed. Six parameters related to the aquifer, the water-resisting properties of the aquifuge and the mining-induced stresses were extracted as the major parameters to construct the ANFIS model. The constructed ANFIS was trained with twenty reported real fault-induced water inrush cases, and another five new cases were used to test the prediction performance of the trained ANFIS. The final results showed that the prediction results of the five cases were completely consistent with the actual situations. This indicates that the ANFIS is highly accurate in the prediction of fault-induced water inrush and suggests that quantitative assessment of fault-induced water inrush using the ANFIS is possible.

In underground near-fault mining, fault reactivation is related to many kinds of mine disasters such as mine water inrush, mine earthquakes, gas outburst, rock burst, roof collapse. pre-evaluation of fault stability in the pre-mining phase is of great significance for predicting possible mine fault-related disasters. In this study, based on the geomechanical analysis of fault slip tendency, a technique to the pre-mining evaluation of fault stability under Andersonian stress system was introduced by extending the original Morris’s theory of fault slip-tendency, effects of fault orientation, in-situ stress and pore fluid pressure on fault stability were analyzed. Taking Shilin coal mine as the research background, a pre-evaluation on the stability of all 15 faults distributed in the whole coalfield at the mining depths of 369 and 514 m was conducted, the analysis results demonstrated that all faults in the Shilin coalfield are quite stable at the two mining depths. The work presented in this study is practical and can provide a quantitative geomechanical way in the analysis of pre-mining fault stability and in the risk pre-assessment of fault-related mine disasters.