Abstract
In recent years, in order to increase the coal recovery rate, the large mining height fully mechanized top-coal caving mining has been widely used because it has the advantages of both fully mechanized mining method and large mining height mining method. When this mining technology is used to exploit thick coal seam under upper goaf, the movement characteristics of the overlying strata and the bearing structure formed by the broken rock are complicated, which results in the abnormal pressure during mining, such as severe coal slabs and hydraulic supports being crushed. The key to solve these problems is to study the movement law and the structural evolution characteristics of the overlying strata during large mining height fully mechanized top-coal caving mining, and the movement characteristics of the overlying strata are all determined by the layer-position of the key stratum. UDEC models with different layer-position of the key stratum are established to investigate the influence of the key stratum position on the support working resistance during large mining height top-coal caving mining. Through comprehensive research, the source of support resistance comes from under different geological conditions was analyzed, and the formula for estimating the maximum support working resistance was deduced. In addition, in order to release the severe pressure during large mining height fully mechanized top-coal caving mining, it is recommended to use hydraulic fracturing method to weaken the key stratum in situ.
Highlights
In China, large mining height fully mechanized mining [1, 2] and fully mechanized top-coal caving mining technology [3] are widely used for thick coal seam
The traditional large mining height fully mechanized mining technology has some shortcomings, such as low production capacity, difficult roadway excavation and maintenance, and large coal loss [4,5,6,7]; and traditional fully mechanized top-coal caving mining technology has the disadvantages of low coal recovery rate, high gangue content, large coal dust, difficult roof management, and so forth [8,9,10,11]
Based on the above research results, the key to solve the existing technical problems of high mining height fully mechanized top-coal caving mining technology is to study the law of overlying strata movement and the structural stability characteristics of large mining height fully mechanized caving mining
Summary
In China, large mining height fully mechanized mining [1, 2] and fully mechanized top-coal caving mining technology [3] are widely used for thick coal seam. The fully mechanized top-coal caving mining technology with large mining height is not yet fully mature, and there are some problems such as the severe appearance of mine pressure, the serious face wall, and the heavy load of hydraulic support [16,17,18]. Based on the above research results, the key to solve the existing technical problems of high mining height fully mechanized top-coal caving mining technology is to study the law of overlying strata movement and the structural stability characteristics of large mining height fully mechanized caving mining. Rough the similar simulation experiment, the structure shape of the key stratum and its influence on the rock pressure in the fully mechanized mining face under the condition of large mining height are analyzed. Using UDEC software, the failure height and collapse characteristics of overlying strata in the mining process of thick coal seam in goaf with the same propulsive length of different layers are analyzed. rough the similar simulation experiment, the structure shape of the key stratum and its influence on the rock pressure in the fully mechanized mining face under the condition of large mining height are analyzed. e model of different interlayer key stratum positions is established to analyze the influence of interlayer key stratum position on overburden movement and structure, and the maximum support strength and maximum working resistance of support are calculated. e disadvantages of the traditional methods to deal with the abnormal mine pressure are analyzed and the solution of weakening the key coal strata in situ with water in goaf and actively preventing and controlling the catastrophe is put forward
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