深埋薄基岩大采高工作面支架阻力分布与急增阻效应分析

Analysis of support resistance distribution and rapid increase resistance effect in deep buried thin bedrock panel with large mining

赵固二矿14030大采高工作面埋深大、基岩薄,顶板来压时支架增阻快,动载冲击频率高。为提高深埋薄基岩顶板控制效果,采用理论分析、现场实测、数值计算等方法分析了大采高工作面支架阻力分布及急增阻效应。结果表明:工作面中部支架平均工作阻力大于上、下部支架,顶板存在动载冲击风险,两端顶板破碎严重,支架阻力低,但易出现支架前倾、倒架问题;快速推进导致支架在来压期间工作阻力明显增大,动载冲击次数增多,非来压期间压力缓和;慢速推进顶板载荷传递充分,支架受力时间长,顶板损伤严重,导致了来压步距较短,来压时顶板动载冲击效应减弱;将支架增阻循环曲线分为三阶段,工作面中部支架在第Ⅰ阶段和第Ⅲ阶段都出现明显急增阻特性,说明工作面中部支架初撑力不足,且顶板压力较大,来压较快,易于发生动载冲击现象;深埋薄基岩大采高工作面冒落拱与拱脚高耸岩梁复合承载结构的失稳过程,是工作面中部支架急增阻的主要原因,通过数值模拟分析,提出将支架刚度维持在50 MN/m时,即可缓解顶板动载冲击,使支架及时让压,同时可最大程度控制支架立柱下降,保证采场煤壁稳定。

The Panel 14030 of Zhaogu No.2 coal mine is a typical deep buried thin bedrock panel with large mining height.As the roof weighting occurs,the support resistance increases rapidly,and the dy-namic load impact occurs at times.In order to improve the control effect of deep buried thin bedrock roof,theoretical analysis,field measurement and numerical calculation are used to analyze the support resistance distribution and rapid increase resistance effect of large mining height working face.It is found that the average working resistance of the support in the middle of the panel is significantly larger than that of the upper and lower supports,and the middle roof exists a risk of dynamic load impact.The roof at both ends of the panel is seriously broken,and the support resistance is low,but it is easy to cause the problems such as forward inclination and collapse of the support.The rapid advance leads to a significant increase in the working resistance of the support during the pressure period,an increase in the number of dynamic load shocks,and a relaxation of pressure during the non-pressure period.In the slow advance stage,the load transfer of the slow advancing roof is sufficient,the stress time of the support is long,and the roof damage is serious,which leads to the short pressure step and the weakening of the dynamic load impact effect of the roof.The resistance-increasing cycle curve of the support is divided into three stages.The middle support of the panel has obvious resistance-increasing characteristics in the first stage and the third stage,indicating that the initial support force of the middle support of the panel is insufficient,and the roof pressure is large,and the pressure is fast,and the dynamic load impact phenomenon is prone to occur.The instability process of the composite bearing structure of the caving arch and the high rock beam at the arch foot is the main reason for the rapid increase of the resistance of the support in the middle of the panel.Through numerical simulation analysis,it is proposed that when the support stiffness is maintained at 50 MN/m,the dynamic load impact of the roof can be alleviated,so that the support can yield pressure in time,and the displacement of the support can be controlled to the greatest extent to ensure the stability of the coal wall in the stope.