预切缝对滚刀破岩裂纹扩展的影响规律研究

Study on the Influence Law of Pre-cutting Groove on the Crack Expansion of Rock Breaking by Disc Cutter

针对硬岩地质条件下传统滚刀破岩出现贯入度低、磨损严重和破岩效率低等问题,许多新型辅助破岩方法被提出,如通过激光、水射流等非接触式破岩方法在岩石上制造预切缝来辅助滚刀破岩。为了明晰预切缝条件下滚刀破岩机理,采用颗粒离散元方法建立预切缝在滚刀侧面(侧置式)和滚刀前面(前置式)两种辅助破岩仿真模型,探究了预切缝深度和间距对滚刀破岩裂纹拓展的影响规律。研究结果表明:1)侧置式辅助破岩模型中,预切缝主要影响裂纹的拓展,诱导破岩过程中侧向裂纹向预切缝底端扩展;前置式辅助破岩模型中,预切缝主要影响裂纹的萌生起裂,在贯入初期只产生侧向裂纹,并促使侧向裂纹向两侧扩展。2)滚刀垂直力和裂纹数量均随着预切缝深度的增加而减小,但滚刀垂直力随着刀间距的增大而增大,裂纹数量则随着刀间距的增加先增大后减小。3)同等条件下,侧置式辅助破岩模型的破岩效率要高于前置式辅助破岩模型,但前置式辅助破岩模型中滚刀的垂直力要远小于侧置式辅助破岩模型中的滚刀垂直力,可通过进一步增加前置式辅助破岩模型中滚刀贯入度来充分利用预切缝辅助破岩。4)滚刀贯入度一定时,侧置式辅助破岩模型适用于预切缝深度大于滚刀贯入度的情况,而前置式辅助破岩模型适用于预切缝深度小于滚刀贯入度的情况。

To solve the problems of low penetration,serious wear and low rock-breaking efficiency during traditional disc cutter rock breaking under the geological conditions of hard rock,many new auxiliary rock breaking methods have been proposed,such as creating pre-cutting grooves on the rock through laser,water jet,and other non-contact rock-breaking methods to assist disc cutter rock breaking.To clarify the rock breaking mechanism of the disc cutter under the condition of the pre-cutting grooves,the particle discrete element method is used to establish two auxiliary rock breaking simulation models for the pre-cutting grooves at the side of the disc cutter(side-type)and in front of the disc cutter(front-type).The influences of the depth of the pre-cutting grooves and the cutter spacing on the propagation of rock-breaking cracks by the disc cutter are explored.The research results show that:1)The pre-cutting grooves in the side-type auxiliary rock-breaking model mainly affect the expansion of cracks,and the lateral cracks propagate to the bottom of the pre-cutting grooves during the process of inducing rock breaking.The pre-cutting grooves in the front-type auxiliary rock-breaking model mainly affect the initiation of cracks,and only lateral cracks are generated at the early stage of penetration,and the lateral cracks are promoted to propagate to both sides;2)The vertical force of the disc cutter and the number of cracks decreases with the increase of the depth of the pre-cutting grooves,while the vertical force of the disc cutter increases with the increase of the cutter spacing,and the number of cracks first increases and then decrease with the increase of the cutter spacing;3)Under the same condition,the side-type auxiliary rock-breaking model is higher than that of the front-type auxiliary rock-breaking model,but the vertical force of the disc cutter in the front-type auxiliary rock-breaking model is much smaller than the vertical force of the disc cutter in the side-type auxiliary rockbreaking model.The auxiliary effect of the pre-cutting grooves can be fully utilized by further increasing the penetration of the disc cutter in the front-type auxiliary rock-breaking model;4)When the penetration of the disc cutter is constant,the side-type auxiliary rock-breaking model is suitable for the case where the depth of the pre-cutting grooves is greater than the penetration of the disc cutter,and the front-type auxiliary rockbreaking model is suitable for the case where the depth of the pre-cutting grooves is less than the penetration of the disc cutter.