周向超前割缝辅助碟形滚刀楔裂破岩性能

Rock breaking performance of disc cutter assisted by circumferential pre-slotting

碟盘滚刀基于底切破岩模式而具有较好的硬岩破碎性能,为进一步提高煤矿井下硬岩巷道机械化掘进效率,以碟盘滚刀为对象,探究了周向超前割缝预裂岩石辅助碟盘滚刀楔裂破岩性能。通过碟形滚刀楔裂破岩实验,明确了碟形滚刀楔裂破岩机理,揭示了周向超前割缝对岩石断裂特性的影响机制,并以滚刀载荷、岩石破碎体积和破岩比能耗为指标综合评价了切削参数和割缝参数对滚刀破岩性能的影响,采用正交试验得到了各因素对破岩性能的影响显著性及滚刀最优破岩性能时对应的参数匹配关系。结果表明:根据滚刀载荷波动和岩石断裂造成的声发射振铃变化特征可将碟形滚刀楔裂破岩过程划分为3个阶段,即压密阶段、应力积聚阶段和崩落阶段;相同切削厚度条件下,与无割缝条件相比,割缝深度和割缝宽度分别为16 mm和3 mm时碟形滚刀破岩载荷和滚刀应力分别降低40%和20%。基于三因素四水平正交试验得到的破岩性能最优条件下切削厚度、割缝深度和割缝宽度的匹配关系为30、16和3 mm,其中切削厚度对碟形滚刀破岩性能的影响最为显著,割缝深度次之,割缝宽度的影响程度最小。滚刀破岩载荷和岩石破碎体积均与切削厚度呈正相关关系,破岩比能随着切削厚度的增加先减小后增大,在30 mm切削厚度下得到最小值;各指标随着割缝深度的增加均呈现出先减小后增大的变化规律,最佳割缝深度为16 mm;当割缝宽度超过3 mm时,各指标受缝宽的影响不显著。周向超前割缝预裂岩石对提高碟形滚刀楔裂破岩性能具有较好提升效果,同时益于改善碟形滚刀受载条件、延长刀具服役寿命,进而为碟形滚刀掘进装备的设计提供一定的指导和参考。

Disc cutter has a better hard rock breaking performance due to its undercutting mode.To further improve the mechanized excavation efficiency of hard rock roadway in underground coal mine,the rock wedged performance of disc cutter assisted by circumferential pre-slotting was investigated.Based on the rock wedged tests by disc cutter,the mechanism of rock wedged by disc cutter has been understood,and the influencing mechanism of the circumferential pre-slotting on rock fracturing has been revealed.The effects of cutting parameters and slotting parameters on the rock breaking performance of disc cutters were comprehensively evaluated by taking the cutter load,rock fragments volume and specific energy of rock-breaking as indicators,and the significance of the effects of various factors on the rock breaking performance and the corresponding parameter matching relationship of the optimal rock breaking performance of disc cutter were obtained by orthogonal test.The results show that the rock wedged process by disc cutter can be divided into three stages based on the characteristics of cutter load fluctuation and acoustic emission ringing caused by rock fracturing,namely,compressive stage,stress accumulation stage and fragmentation stage.At the condition of same cutting depth,the cutter load and stress with a slotting depth and width is 16 mm and 3 mm decreases more than 40%and 20%respectively compared to that without pre-slotting condition.Based on the orthogonal test with three-factor and four-level,the matching relationship between cutting depth,slotting depth and slotting width under the optimal rock breaking performance is 30,16 and 3 mm.The cutting depth has the most significant effect on the rock breaking performance of disc cutter,followed by slotting depth and slotting width.The cutter load and rock fragments volume are positively correlated with cutting depth.The specific energy of rock breaking decreases first and then increases with the increase of cutting depth,and the minimum value is at 30 mm.Each index decreases first and then increases with the increase of slotting depth,and the optimal value is 16 mm.When the slotting width exceeds 3 mm,the influence of slotting width on each index is not significant.Circumferential pre-slotting has a good effect on improving the rock wedged performance of disc cutter.At the same time,it is beneficial to improve the loading conditions of disc cutters and prolong the service life of cutters,so as to provide some guidance and reference for the design of disc cutter.