Abstract
Water inrush disasters are extremely prone to occur if the coal seam floor contains a confined aquifer. To find out the failure behavior of coal seam floor of paste filling working face, a beam-based theoretical model for the floor aquifuge was built, and then, the water inrush risk was evaluated based on the thickness of floor aquifuge. Next, the floor failure characteristics of the paste filling face was numerically studied and the effects of the filling interval and long-term strength of the filling body on the floor failure depth, stress and displacement distributions, and plastic zone were explored. The results showed that the theoretical model for evaluating the safety of the floor of the paste filling face based on the empty roof distance is proved to be consistent with that of the empirical formula judged based on the assumption that the paste filling working face was regarded as a cut hole with a certain width. The filling interval has a significant effect on the stress concentration of the surrounding rock, failure depth of floor, and roof-floor convergence. The smaller the filling interval is, the smaller their values are. When the filling rate is 98%, the long-term strength of the filling body is 5 MPa, and the floor failure depth is not more than 4 m. In contrast, the strength of the filling body has no obvious influence on the floor failure depth, but it has a certain impact on the roof-floor convergence. From the perspective of reducing floor failure depth, there is no need to increase the long-term strength of backfill, but it is necessary to increase the early strength of backfill so as to reduce the width of the equivalent roadway.
Highlights
China’s hydrogeological conditions are complicated, and coal mines are seriously threatened by mine water disasters
When the stress transferred from the filling body to the floor reaches the water pressure of the floor confined aquifer, i.e., the floor aquifuge is in a state of force balance
When the strength of the rear filling body is increased enough to transfer the balanced hydraulic stress level, the floor aquifuge is in a state of force balance here, and the floor aquifuge between the abovementioned filling body and the coal wall of the working face can be simplified as a beam fixed on both sides
Summary
China’s hydrogeological conditions are complicated, and coal mines are seriously threatened by mine water disasters. The hydraulic failure of the coal seam floor can result in the formation of a water inrush channel, which is an important factor causing water inrush disaster from the floor. Zhang and Liu [14] developed the theory of plate and shell and analyzed the failure mechanism of coal seam floor using elastic-plastic mechanics method. In order to solve the threat of pressurized water to the working face and to evaluate the risk of water inrush from paste-filled working face, this paper is aimed at revealing the failure characteristics and laws of the coal seam floor in paste filling mining. This work is very useful for the control and prevention of the water inrush in paste backfill mining
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
