Experimental Research on Characteristics of Fault Activation and Confined Water Rising

Abstract

Water inrush due to fault activation in deep coal mining is the main type of water disaster in central and eastern China. This paper analyzed the primary form and mechanism of fault activation that triggers water inrush and derived the critical conditions for fault activation. The WuGou coal mine is used as a geological example, and the characteristics of the fault activation and mechanism of the confined water rising were researched by similar simulation experiments. The results provide the following conclusions. (1) There are three forms of fault activation that trigger water inrush: continuous fault, hidden fault and associated fault activation. (2) Mining causes high abutment pressure in a coal seam; this pressure transfers to the floor, causing damage and failure. The maximum failure depth occurs when the overlying strata is in a critical fractured state. The cracks of the floor gradually close in the goaf. (3) The fault activation causes water inrush and exhibits four stages: fault zone yielding caused by high stress, cracking and extending of the fault zone, movement and slippage of the fault zone, and confined water rising. (4) The influence factors of the confined water rising were analyzed. The experimental results show a negative correlation between the confined water height and distance to the fault zone and a positive correlation among the confined water pressure, fault zone width and confined water height. In addition, a strong–weak–strong change law of the confined water pressure with height is observed.