What question did this study set out to answer?

To investigate the mechanisms of water influx from minor faults during coal mining and identify influential factors.

January 22, 2026Open Access

Multi-Factor Coupled Numerical Simulation and Sensitivity Analysis of Hysteresis Water Inundation Induced by the Activation of Small Faults in the Bottom Plate Under the Influence of Mining

Key Points

To investigate the mechanisms of water influx from minor faults during coal mining and identify influential factors.
Developed 17 numerical models using FLAC3D simulation software.
Examined stress, displacement, plastic zones, and seepage fields in relation to four factors.
Conducted gray relational analysis to assess sensitivities of various factors.
Upper and lower plates of minor faults showed discontinuous deformation due to mining.
Higher aquifer pressure and larger fracture zones increased fault activation and water flow.
Increased distance from the coal seam to the aquifer decreased water influx.

Abstract

A major danger that significantly raises the possibility of deep coal mining accidents is the delayed water influx from the bottom plate, which is brought on by the activation of tiny faults brought on by mining at the working face of the restricted aquifer. This study develops 17 numerical models utilizing FLAC3D simulation software 6.00.69 to clarify the activation and water inburst mechanisms of minor faults influenced by various parameters, incorporating fluid–solid coupling effects in coal seam mining. The developmental patterns of the stress field, displacement field, plastic zone, and seepage field of the floor rock layer were systematically examined in relation to four primary factors: aquifer water pressure, minor fault angle, fracture zone width, and the distance from the coal seam to the aquifer. The results of the study show that the upper and lower plates of the minor fault experience discontinuous deformation as a result of mining operations. The continuity of the rock layers below is broken by the higher plate’s deformation, which is significantly larger than that of the lower plate. The activation and water flow into small faults are influenced by many elements in diverse ways. Increasing the distance between the coal seam and the aquifer will make the water conduction pathway more resilient. This will reduce the amount of water that flows in. On the other hand, higher aquifer water pressure, a larger fracture zone, and a fault that is tilted will all help smaller faults become active and create channels for water to flow into. The gray relational analysis method was used to find out how sensitive something is. The sensitivities of each factor to water influence were ranked from high to low as follows: distance between the aquifer and coal seam (correlation coefficient 0.766), aquifer water pressure (0.756), width of the fracture zone (0.710), and angle of the minor fault (0.673). This study statistically elucidates the inherent mechanism of delayed water instillation in minor faults influenced by many circumstances, offering a theoretical foundation for the accurate prediction and targeted mitigation of mine water hazards.

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