A fuzzy comprehensive evaluation of coal mining near unconsolidated aquifers

Based on fuzzy mathematic theory and related statistical data, the entropy weight method was used to evaluate the weights of the key factors affecting the mining safety under unconsolidated aquifers. Moreover, GIS was applied to determine each factor's membership degree, therefore a fuzzy comprehensive evaluation model was established based on entropy weight. In the panel No. 01 of a coal mine in Shandong Province, six factors were chosen as evaluation indexes, including the thickness of overburden rock, fault structure, the thickness of the lowest Quaternary clay, the specific inflow of the bottom sand aquifers, the thickness of mining and the height of water flowing fractured zone. The evaluation set of the degree of feasibility was determined {lower, low, medium, high, very high}. According to the related codes for mining safety under water bodies, each factor's membership was determined by GIS and each factor's weight was deducted from mining data. A comprehensive evaluation for the mining safety under the unconsolidated aquifers shows that it is feasible when the extraction height is 2.00 m for the panel. No. 01 by taking appropriate measures targeting on some unsafe factors. No serious disturbances and accidents such as groundwater inrush and quicksand have happened during mining and the applicability of the fuzzy evaluation method has been verified preliminarily.