不同岩石和围压下刃形对滚刀破岩性能的影响

Effects of TBM Cutter Profile on Rock Fragmentation Under Different Rock Type and Confining Pressure Conditions

滚刀位于全断面隧道掘进机(TBM)最前端,与岩石直接发生接触,是执行破岩掘进的关键零部件.研究TBM滚刀截面轮廓(刃形)对其破岩性能的影响机理和规律,对指导工程实际中滚刀选型与设计、提高TBM掘进效率具有重要意义.首先建立二维颗粒流离散元模型,针对工程中最常用的平头滚刀和圆弧滚刀,选取两种强度不同的岩石并对其中一种施加固定10 MPa围压;然后,开展滚刀破岩仿真,通过分析比能、破岩体积、刀具载荷、裂纹数量等结果,对滚刀刃形与岩石破碎的关联性进行研究;最后,通过缩比滚刀破岩实验验证数值分析所得结论的正确性.分析结果表明:滚刀刃形对其破岩性能影响显著,在本文所涉及参数范围内,对于多数岩石强度与围压组合,圆弧滚刀比能均低于平头滚刀比能,平均降低19.8%;圆弧滚刀破岩力比平顶滚刀破岩力平均低32.6%,表明破岩过程中圆弧滚刀做功较少,而二者产生的岩石碎片总体积相差不大(平均差值7%),则圆弧滚刀破除单位体积岩石所消耗的能量更少.综上所述,两种常用滚刀刃形相比,在岩石强度与围压较高的地层中可考虑优先选用圆弧滚刀.

The disc cutters located at the front end of a full-section tunnel boring machine(TBM)play an important role in the rock breaking process.The influence of the cross-sectional profile of the disc cutter on the rock fragmentation is important to study,to improve the TBM tunneling efficiency in engineering practice.Here,a two-dimensional particle flow model for rock cutting is established.Aiming at the flat-tip and circular-tip cutters,which are commonly used in engineering,two kinds of rocks with different strengths are selected,and a fixed confining pressure of 10 MPa is applied to one of the rocks.Then the rock cutting simulation is carried out,and the correlation between the cutter profile shape and the rock fragmentation is studied by analyzing the results of specific energies,rock fragment volumes,cutting forces,and crack numbers.A reduced-scale rock cutting experiment is performed to verify the correctness of the conclusions obtained from the simulations.The simulation results show that the cutter profile has a significant influence on the rock cutting performance.The specific energy of the circular-tip cutter is lower than that of the flat-tip cutter under most rock strengths and confining pressure conditions.The average reduction in the specific energy is 19.8%because the cutting force of the circular-tip cutter is 32.6%lower than that of the flat-top cutter on average.This indicates that the circular-top cutter does less work when tunneling,even though the total volumes of rock fragments created by the two types of cutters are similar(the average difference is 7%).Therefore,the circular-top cutter consumes less energy to break the same volume of rock.In summary,of the two commonly used cutter profiles,the circular-tip cutter is preferred for hard rock and high confining pressure tunneling.