厚硬顶板高强度开采覆岩破断 及来压规律研究

Study on the law of overlying rock breaking and weighting in high-intensity mining with thick and hard roof

针对榆神矿区厚硬顶板高强度开采条件下,工作面煤壁片帮大、支架结构件损坏等强矿压问题,采用了数值计算、理论分析和微震监测等技术手段,对工作面覆岩破断运动及来压规律进行了分析研究。结果表明,厚硬顶板破断具有明显的垂向分区下沉特征,高、低位岩层之间较大的垂向离层空间和自下而上顺次交替垮落孕育了顶板“高+低层位组合破断”的时空基础;“小周期”来压期间内,来压强度将随着直接顶破断发育高度的降低而减弱,直接顶碎胀系数的增大将有利于来压强度的降低;“大周期”来压期间内,中高位岩层垂向破断高度和走向破断步距的增大都将引发来压强度上升,厚硬关键层的组合破断是“大周期”来压增强的关键诱因。针对该条件下的强矿压防治,提出了“弱化低位顶板、优化破断结构”和“弱化高位顶板、改变破断次序”的技术思路,并取得了较好的应用效果。

In response to the strong mine pressure problems such as serious coal wall caving and support structure damage during high-intensity mining in working face with thick and hard roof in Yushen mining area,numerical calculations,theoretical analysis,and microseismic monitoring techniques were used to analyze and study the movement law of overlying rock breaking and the weighting law of the working face.The results indicated that the breaking of thick and hard roof had obvious characteristics of vertical zone subsidence,and the large vertical separation space between high and low rock layers and the sequential alternating collapse from bottom to top had nurtured the spatiotemporal basis of high and low layer combination fracture of the roof;during the small-cycle weighting period,the weighting strength would weaken with the decrease of the height of direct roof breaking and development,and the increase of the direct roof fragmentation coefficient would be beneficial for the decrease of weighting strength;during the large-cycle weighting period,the increase of vertical fracture height and strike fracture step distance of medium-high-level rock layers would lead to an increase in weighting intensity,and the combination breaking of thick and hard key layers was the key factor for increased large-cycle weighting.Aiming at the strong mine pressure control under this condition,the technical ideas of weakening the low-level roof to optimize the fracture structure and weakening the high-level roof to change the fracture sequence had been proposed,which had achieved good application results.