节理倾角对岩石隧道掘进机破岩特性影响的数值研究

为研究节理特征对岩石隧道掘进机（TBM）盘形滚刀破岩特性的影响，采用颗粒离散元法（PFC）建立了不同节理倾角下双滚刀破岩模型并进行数值仿真，研究不同节理倾角对应的岩石破碎模式、裂纹数目和破岩比能。结果表明:（1）倾斜节理的存在改变了裂纹扩展规律，裂纹呈现不对称性扩展模式。节理的存在改变了裂纹的延伸方向，限制主裂纹向下扩展。节理倾角越大，对主裂纹的萌生与扩展起到的阻碍作用越明显。节理倾角较小时，裂纹沿节理倾向延伸，有利于双滚刀间裂隙的贯通，有利于岩石碎屑的剥落；（2）节理倾角对剪切裂纹的影响较小，主要影响拉裂纹数目。总裂纹数随节理倾角的增大先增大后减小，当节理倾角为30°时达到最大。从滚刀破岩效率来看，节理岩体存在一个最优节理倾角。当节理倾角在30°附近时，破岩比能最小，破岩效率最高。基于颗粒离散元法PFC2D可以较好地模拟节理岩体双滚刀破岩过程，弥补室内试验无法进行细观特性研究的缺陷。

Numerical simulation on the effect of joint orientation on rock fragmentation by TBM disc cutters

In order to study the effect of joint characteristic on rock fragmentation mode，the jointed rock indentation process by TBM disc cutters was simulated by using the particle discrete element method，and specific energies and crack numbers at different orientations were collected to analyze the rock fragmentation process.The main results are as follows:（1）The joint orientation can significantly influence the crack initiation and propagation as well as the fragmentation mode.The crack initiation and propagation is no longer symmetric，and joints will change the initial direction of crack propagation，especially at vertical direction.The impediment to crack initiation and propagation is more obvious with the increase of joint inclination angle，while joints with small inclination angle facilitate the cracks to extend along the joints and rock debris to chip off.（2）Joint orientation mainly affects tensile cracks and crack number increases initially with the joint inclination angle and then decreases after the peak value.There is an optimal joint inclination angle in jointed rock masses and when joint inclination angle α=30°，specific energy is the smallest and the rock fragmentation efficiency of disc cutters can reach the highest.Based on particle discrete element method，PFC2D can well reproduce the fragmentation process，and numerical simulation can be used to study the microscopic properties of jointed rock which cannot be involved in laboratory experiments.