多煤层上覆破断顶板群结构演化及其对下煤层开采的影响

采用理论分析、数值模拟和现场监测等方法，首先建立多煤层破断顶板群结构演化模型，推演不同煤层开采时破断顶板群发育扩展高度，获得了“遗留煤柱-破断顶板群结构”共同作用下工作面支护强度计算公式；其次通过数值模拟揭示了破断顶板群结构发育扩展规律；最后进行现场监测验证。结果表明：侏罗系煤层群间距较小，间隔岩层极易破断，易与上层煤已垮落和破断的顶板结构连接，形成破断顶板群结构；虽然石炭系与侏罗系煤层间距较大，但侏罗系煤层破断顶板群岩层重量通过遗留煤柱向下传递，并与石炭系煤层破断顶板共同作用于工作面支架上，致使石炭系煤层工作面支架压力显著增大。本研究有效解释了多煤层开采时下煤层发生强矿压的原因，为大同矿区及类似矿井多煤层开采围岩控制提供了依据。

Structural evolution of breaking roof group of multiple coal seams and its influence on lower coal seam mining

Based on theoretical analysis,numerical simulation and field monitoring,an evolution model of breaking roof group structure of multi-coal seams was established,the development and extension height of breaking roof group were derived when mining successive coal seams,and the formula of mining face support strength was given under the interaction of remained coal pillars and breaking roof group.Subsequently,the extension law of breaking roof group height was studied using numerical simulation and the site validation was also carried out.The results show that: the space between the coal seams of Jurassic system is small and the interval layer is easily broken and connected to the caving and broken roof structure of upper coal seam which leads to the formation of a breaking roof group structure.Though the space between Jurassic and Carboniferous system is large,the weight of breaking roof group of Jurassic system passes down through remained coal pillars and acts on the mining face support together with breaking roof group strata of Carboniferous system,which results in the significant increase of support pressure in mining face of Carboniferous system and strong ground pressure occurs.This paper explains the reason why strong ground pressure appears in lower coal seam when mining multiple coal seams,which could provide the basis for the surrounding rock control in multi-coal seams mining at Datong mining area and similar coal mines.