双节理岩体TBM滚刀破岩过程数值模拟

为了研究节理特征对全断面掘进机(tunnel boring machine, TBM)盘形滚刀破岩的影响,采用颗粒流方法建立盘形滚刀与含平行双节理岩体的二维数值模型,进行不同节理倾角和间距的30组数值试验,根据数值试验结果研究岩体破裂模式、滚刀竖向接触力峰值随节理倾角和间距的变化规律、滚刀破岩过程中细观裂纹扩展规律。研究结果表明:不同的节理特征下,滚刀破岩可以分为4种基本的破裂模式;滚刀竖向接触力峰值随节理倾角的增大呈现先减小后增大的趋势,在节理倾角为30°或45°时最小,在节理倾角为90°时最大;滚刀竖向接触力峰值随节理间距的增大总体上呈现增大趋势;随滚刀的贯入,滚刀竖向接触力与细观裂纹个数有3个关联的变化阶段。通过研究TBM滚刀与节理岩体相互作用机制,揭示不同节理特征对滚刀破岩的影响规律,对TBM滚刀的合理设计和施工有一定的指导意义。

Numerical simulation of rock fragmentation process by TBM cutter in double-joint rock mass

Effects of joint characteristics on rock fragmentation process by full-face rock tunnel boring machine(TBM)disc cutter was studied by numerical simulation using the particle discrete element method. A numerical model including double-joint rock mass and a disc cutter was established. 30 sets of numerical simulation tests with different joint spacing and joint angle were carried out to explore the failure modes of rock mass, study the variations of peak value of vertical contact force of cutter with joint spacing and joint angle, and analyze the characteristics of microscopic cracks growth during the rock fragmentation process. Results showed that four rock fragmentation modes were proposed as the joint characteristics changes; the peak value of vertical contact force of cutter first decreased and then increased with joint angle, and the minimum value was at 30° or 45° and the maximum value was at 90°; the peak value of vertical contact force of cutter generally increased with joint spacing; the amount of microscopic cracks was related to the vertical contact force of cutter and the relation was divided into three stages. These conclusions had certain guiding significance for the rational design of TBM cutter and TBM construction.