Study on prediction of water inrush hazard in roof of roadway driving

Coal seam roof water disaster is one of the major disasters that threaten safety production of coal mines. In recent years, roof water inrush accidents often occur during roadway excavation in shallow coal seams in Northern Shaanxi. The main reason is that the Jurassic weathered bedrock aquifer is relatively soft and water-rich. In the area where the thickness of the overlying aquifer is relatively thin, the surrounding rock disturbance connects the weathered bedrock aquifer during roadway excavation or directly expose the weathered bedrock aquifer to induce water inrush in the heading face, or even water inrush and sand inrush (mud). Therefore, it is very necessary to predict the dangerous area of water inrush from the roof of roadway excavation. In this paper, taking 4-2 coal mining in Hongliulin Mine field as an example, five main controlling factors, such as weathering bedrock aquifer thickness, weathering degree, lithological combination, number of sandstone layers and paleo-topographic elevation, were selected.Water richness of weathered bedrock aquifer was predicted by random forest (RF) algorithm, and the water-rich zoning prediction map was compiled.At the same time, the lithologic characteristics of roadway surrounding rock were analyzed, and the multivariate linear and exponential function regression prediction mathematical model of the thickness of the loose circle was constructed based on the measured data of the thickness of the loose circle, and the prediction result of the thickness of the loose circle of the surrounding rock was obtained. The difference between the thickness of the loose ring and the thickness of the loose ring was used as the main index to predict the safety partition of the roadway excavation roof, and the safety partition prediction map of the roadway excavation roof was compiled. On this basis, the water-rich zoning prediction results of weathered bedrock aquifer and the safety zoning prediction results of roadway driving roof were analyzed by using GIS software, and the zoning prediction map of water inrush risk of roadway driving roof was obtained. The results show that the dangerous area of water inrush from the roof of roadway in 4-2 coal seam and the larger dangerous area are mainly located near the denudation boundary of 4-2 coal seam in Beiyi area, which is basically consistent with the actual position of water inrush. Therefore, the prediction method and results can be used as an important basis for water prevention and control in Hongliulin Coal Mine, and can also provide a reference for other mines with similar geological conditions. © 2022 China Coal Society. All rights reserved.