综采面多层坚硬顶板破断特征及其安全控制研究

祁东煤矿8_2煤层覆岩存在多层厚度较大坚硬岩层,初次跨落步距大,周期断裂悬顶长,严重危害工作面的安全生产。通过分析坚硬顶板的岩梁结构、力学特性,建立了初次来压双固支梁模型,判断出关键层的位置,获得了顶板初次垮落及周期垮落步距。并建立了有矸石支撑的周期跨落悬臂梁模型,根据平衡关系计算得到给定支架载荷下的合理悬顶长度。采用超前深孔预裂爆破技术弱化坚硬顶板,设计了合理爆破参数。开采实践表明,采用的爆破技术实现了对坚硬顶板的有效控制,减小了基本顶跨落步距,降低了来压程度,保证了工作面的安全正常开采。

Study on the Breaking Characteristics and Safety Ccontrol of Multilayer Hard Roof in Fully Mechanized Mining Face

There are thick and hard rock strata above the 82 coal in Qidong Coal Mine.Its characteristics of large primary bestraddle distance and long periodic fracture hanging roof constitute a serious threaten to the safety production of working mine.An initial pressure double fixed beam model is established based on the analysis of rock beam structure and the mechanical properties of hard roof.The location of key strata is determined,as well as the first and cycle caving distance.A cycle span cantilever beam model with gangue supporting is established,and the reasonable overhanging length is obtained under given load according to the equilibrium relationship.According to the characteristics of geological conditions of coal mine,advanced deep hole pre splitting blasting technique is used to soften the hard roof with reasonable blasting parameters.Mining practice shows that effective control of hard roof is realized by the blasting technology,which reduces the basic roof span,reduces the pressure,and ensures the safety of working surface.