基本顶破断失稳在急斜煤层放顶煤开采中的作用

Function of destruction and instability of basic roof in top coal caving of steep seams

为研究急斜煤层水平分段放顶煤开采过程中基本顶破坏活动对工作面的影响,根据急斜煤层基本顶具有倾斜狭长板的特点,运用弹性薄板理论对基本顶岩层进行了拉应力分析,得出了顶板破断的判别准则,建立了基本顶初次破断后形成的“铰接结构”的力学模型。通过分析结构滑落失稳和回转失稳的力学条件,指出危险点是上铰接点。研究表明急斜放顶煤开采围岩结构虽然与缓斜煤层长壁放顶煤不同,基本顶(老顶)和直接顶只是在工作面的一侧,但仍然不能忽视它对工作面矿山压力显现的影响。铰接结构的上铰接点是岩层控制的关键点,这为现场实施充填以防止基本顶失稳的动力作用,提供了理论依据。

In order to study the basic roof＇s destruction movement that affects working face in horizontal section top coal caving in mining steep seams, this paper analyses tension of roof using elastic and thin board theory and obtains criterion of roof destruction based on long and narrow thin board. Moreover, it establishes mechanical model of roof structure after first destruction, and points out that sur-hinge-point is dangerous point by analyzing mechanical condition of sliding instability and rotary instability about hinge structure. The result of research reveals that strata behavior of basic roof and immediate roof on working face can not be neglected in mining steep seams. Theory that the sur-hinge-point is pivotal point provides theoretical basis for the filling to prevent the instability of the basic roof.