No abstract

In order to ensure the safe production of Gequan coal mine, it is important to carry out a water bursting evaluation of the coal seam floor. This study selects vulnerability index method based on AHP as the evaluation method. Based on the analysis of the geological data in study area, water pressure, measured specific yield, equivalent thickness of effective aquiclude, brittle rock thickness under mining pressure damage zone, distribution of faults, distribution of collapse column, distribution of endpoints and intersection of fault and fault-scale index are taken as the evaluation index. As there are two aquifers in the lower part of the coal seam that are a threat to mining, the author evaluated Benxi limestone aquifer and Ordovician limestone aquifer separately, the reliability of the results was verified by comparing the results obtained with the water bursting point and some of the boreholes. The results of the evaluation provide guidance on the safe production of coal mines.

A water-bursting evaluation of the coal seam floor is critical to ensure safety of coal mine production. The vulnerability index method based on AHP is selected for this study’s evaluation method. Water pressure, measured specific yield, equivalent thickness of effective aquiclude, brittle rock thickness under mining pressure damage zone, distribution of faults, distribution of collapse column, distribution of endpoints, and the intersection of fault are taken as the evaluation index based on the analysis of geological data in the study area. The authors assessed the threat posed by the two aquifers in the lower portion of the coal seam. Separate evaluations were conducted on the Benxi and Ordovician limestone aquifers. The results’ veracity was confirmed by comparing the obtained results to the water bursting point and a few boreholes. The evaluation results provide recommendations for the safe operation of coal mines.

To obtain the evaluation results that are more in line with the water-richness of thin limestone aquifers for ensuring the safety of coal mine production, dewatering test and hydrochemical analysis were conducted on Benxi thin limestone aquifer to explore and quantify the hydraulic connection between the Ordovician limestone aquifer and the thin limestone aquifer in Benxi formation. Based on the characteristics of water-bearing media, such as aquifer thickness, core recovery, flushing fluid consumption and permeability coefficient, the CRITIC weighting method was used to determine the weight of each factor’s influence on the water-richness of thin limestone aquifers, so as to establish the model for evaluating the water-richness of thin limestone aquifer in Benxi formation, and draw the thematic map of the main controlling factors of the aquifers. Then, the information was normalized and superimposed using the multi-source information fusion technology, thereby obtaining the zoning of the aquifer per different water-richness. The evaluation results show that the thin limestone aquifer in Benxi formation can be divided into five areas, i.e. “strong, relatively strong, medium weak, relatively weak and weak ” areas. With a stronger hydraulic connection with the Ordovician limestone aquifer, the northwest part of the research area has a greater water-richness than the southeast part, which was verified by the pumping test carried out in the study area.