采场上覆大厚度坚硬岩层破断规律的力学分析

MECHANICAL ANALYSIS OF RUPTURE REGULARITY OF HARD AND MASSIVE OVERLYING STRATA OF LONGWALL FACE

利用两端嵌固梁考虑体积力的力学模型,对厚层坚硬顶板的破断规律进行分析。利用岩层中应力场的分布,提出了大厚度坚硬岩层3种破坏方式的力学判断方法,分别为(1)大厚度坚硬岩层中存在弱面和不存在弱面时两种状态下的剪开,从而导致其“关键性”下降;(2)全厚度范围内的压剪破坏;(3)紧靠端面的拉断破坏。从而为煤矿控制大厚度坚硬岩层的破断规律提供理论依据。现场实例检验表明,此方法可用于老顶初次断裂形态和步距的预测。

Based on the mechanical model of fixed beam with gravity in account, the rupture regularity of hard and massive roof of longwall face is analyzed. The structure of the main roof before its initial rupture is considered as the fixed beam, and the gravity of hard roof is considered as the centralizing force. By using elastic theory and analyzing the stress field of fixed beam under gravity, the mechanics judgement model of the overlying strata in three kinds of possible movement is suggested, which are that (1) the shearing with and without the weak interbedding to directly cause the key falling of strata, (2) rupture resulting from pressure and shearing in the whole strata, and (3) rupture of the strata close to two ends of beam. The suggested mechanics judgement model was tested by field experiments, and it is useful for the prediction of the initial rupture and span of the main roof of the hard and massive strata.