为探究不同围压下TBM盘形滚刀的破岩效率与破碎岩片的破坏模式，采用离散元软件PFC2D，基于伺服原理及线性平行黏结理论，通过对花岗岩进行参数标定生成仿真岩石模型，进而建立滚刀二维仿真破岩模型。在滚刀破岩模型的基础上分别设置1、5、10、15、20、30 MPa 6种围压工况，并在6种围压工况下进行滚刀侵入岩石内部5 mm的仿真模拟，对岩石内部微裂纹的扩展、滚刀破岩比能耗、张拉剪切裂纹数量的变化以及破碎岩片的破坏模式进行研究。研究结果表明： 1)随着围压的增大，岩石内部裂纹的破坏模式由沿晶裂纹逐渐向穿晶裂纹转变，剪切裂纹占比由9.4％（围压为1 MPa）上升到21.3％（围压为30
MPa）。2)在围压为10 MPa的工况下，两滚刀间裂纹贯通，脱落的岩片体积较其他5种围压工况下明显偏大，此时破岩比能耗较低，破岩效果较好。3)滚刀侵入岩石5 mm后，随着围压的增大岩石内部的裂纹在径向上的扩展被限制。
The authors investigate the rock-breaking
efficiency of the disc cutter in tunnel boring machines and the damage modes of
the crushed rock slices under different surrounding rock pressures. Based on
the principles of servo and linear parallel bonding theory, the discrete
element software PFC2D is employed to establish a two-dimensional
simulation model of the rock-breaking process,
calibrated with parameters specific to granite. Six surrounding rock pressure
conditions of 1, 5, 10, 15, 20, and 30 MPa are set and the cutter penetrating
the rock by 5 mm is simulated. The propagation of microcracks in the rock, the
specific energy consumption of the cutter during the breaking process, the
evolution of tensile shear cracks, and the failure modes of the broken rock
pieces are analyzed. The results reveal the following: (1) As surrounding rock
pressure increases, the internal rock cracks transition from along-crystalline to through-crystalline cracks,
with the proportion of shear cracks rising from 9.4% to 21.3% at 1 and 30 MPa,
respectively. (2) At a surrounding rock pressure of 10 MPa, the cracks within
the two disc cutters become interconnected, leading to the generation of larger
rock fragments compared to the other five pressure conditions. Consequently,
the specific energy consumption is reduced, indicating a more effective rock-breaking performance. (3) Following a 5 mm penetration of the disc
cutter into the rock, the radial propagation of cracks is constrained as the
surrounding rock pressure increases.
