大倾角大采高开采支架动载失稳机理及控制

Dynamic instability mechanism of support and its control in longwall mining of steeply dipping coal seam

动载下支架(群)稳定性控制是大倾角煤层开采难题之一,以大倾角大采高综采工作面支架为研究对象,采用现场实测、物理模拟、理论分析和数值模拟等研究方法,总结了大倾角大采高坚硬顶板工作面典型动载的特征,分析了支架在多维动载作用下的失稳机理,提出支架动态稳定性控制对策。结果表明:周期来压时大倾角大采高工作面对支架顶梁或掩护梁易产生来压动载,来压时垮落顶板易产生正压冲击型动载和后推冲击型动载,垮落矸石滑滚易造成架间(侧推)动载。给出了不同影响因素下支架下滑和转动基本运动模式及其耦合状态的动力学方程,得出了支架转动(倾倒趋势)和架间作用力随着顶板法向载荷的减小、顶板切向载荷的增大、顶板偏载程度的增大和采高的增大而增大。数值模拟表明:在正压冲击作用下,支架后柱受载大于前柱;后推作用下,立柱底部受载大于中上部;架间作用时,同一支架内上部立柱受载大于下部,上方支架受载大于下方支架,且均具有明显的非对称受载特征。基于研究结论,提出了坚硬顶板超前周期性爆破弱化、降低底板比压、增设双向侧推装置、采用擦顶带压移架等措施,现场实测表明有效降低了动载对支架稳定性的影响。

Stability control of supports under dynamic load is one of the challenges of mining steeply dipping seam.The research object is to study the dynamic load destabilisation mechanism of the support for high cutting and steeply dipping mining working face by using field measurement,physical simulation,theoretical analysis and numerical simulation.The characteristics of typical dynamic loads on hard roof working face with thigh cutting and steeply dipping mining working face are summarized,and the destabilization mechanism of the sup-port under the action of multi-dimensional dynamic loads is analyzed.The results show that when the periodic weighting,the high cutting and steeply dipping mining working face is easy to produce the incoming pressure dynamic load on the top beam or caving shield,when the top plate collapses,it is easy to produce the positive pressure impact type dynamic load and back push impact type dynamic load,and the collapsed gangue slip and roll is easy to cause the inter-frame(side push)dynamic load.The kinetic equations of the basic modes of motion of the support sliding and rotating and their coupling states under different influencing factors are given,and it is concluded that the support rotation(tilting tendency)and the inter-frame force increase with the decrease of the normal load of the roof plate,the increase of the tangential load of the roof plate,the increase of the degree of deflection of the roof plate and the increase of the mining height.Numer-ical simulation shows that under the action of positive pressure impact,the support rear column is more loaded than the front column;un-der the action of rear push,the bottom of the column is more loaded than the middle and upper part;when the action between frames,the upper column in the same support is more loaded than the lower part,and the upper bracket between brackets is more loaded than the lower bracket,and all have obvious asymmetric loading characteristics.Based on the findings of the study,measures such as weakening the hard top plate by overrunning periodic blasting,reducing the specific pressure of the bottom plate,installing additional bi-directional lateral pushing devices and using touch top with pressure to move the support were proposed to effectively reduce the impact of dynamic load on the stability of the support.