基于煤壁“拉裂-滑移”力学模型的支架护帮结构分析

针对坚硬厚煤层大采高综采工作面极易发生煤壁片帮的问题,以红柳林煤矿7.0 m大采高综采实践为基础,分析了煤壁片帮的应力路径效应,将硬煤煤壁片帮细分为拉裂破坏与滑移失稳两个阶段,建立了坚硬厚煤层煤壁片帮的拉裂-滑移力学模型,得出了煤壁的拉裂破坏深度、宽度与煤体强度、开采高度的关系及液压支架应具有的"临界护帮力",分析对比了2种液压支架护帮装置的结构特点与力学特性。研究结果表明,煤体发生拉裂破坏只是煤壁片帮的必要非充分条件,煤壁最终是否发生片帮,还取决于拉裂破坏体在液压支架与矿山压力作用下是否发生滑移失稳。液压支架很难抑制煤壁发生拉裂破坏,但可以有效防止拉裂破坏体发生滑移失稳。液压支架护帮装置采用伸缩梁与护帮板分开结构设计,具有对煤壁的支护作用力大、结构强度与可靠性高等显著优点。

Hydraulic support protecting board analysis based on rib spalling “tensile cracking-sliding” mechanical model

In order to overcome the problem of rib spalling at a full mechanized mining face with large mining height in hard and thick coal seam，the effect of stress path in the process of rib spalling was analyzed based on the practice of 7.0 m mining height in Hongliulin Mine，China.The process of hard coal seam rib spalling were divided into tensile cracking damage and sliding instability.The rib spalling of tensile cracking sliding mechanical model for hard and thick coal seam was established，which acquired the relationship between the rib cracking damage depth，width and coal mass strength，mining height，and the critical protecting force of hydraulic support.The structural features and mechanical property of two type hydraulic support protecting board were analyzed.The results show that the coal mass tensile cracking damage is a necessary，but not sufficient，condition for rib spalling，whether the rib spalling will finally occur depending on whether the cracking damage body will slide instability under the action of hydraulic support and mine pressure.It was hard for hydraulic support to stop the coal mass tensile cracking，but which can guard against the cracking damage body sliding instability.The hydraulic support protecting board adopts the design with telescopic girder and face guard separately，which has the remarkable advantages of bigger supporting force for rib，higher structural strength，and higher reliability.