切槽对TBM刀具破岩机制的影响研究

高压水射流与机械滚刀相联合破岩技术的出现，改变了传统隧道掘进机（tunnel boring machine，简称TBM）的作业方式。以高压水射流在滚刀两侧岩体切槽的破岩模式为研究对象，开展常截面滚刀压头贯入不同预切槽深度白砂岩板状试样的试验和数值模拟计算分析，对破裂后图像进行DIC分析，研究发现：切槽的存在，阻断了刀具贯入裂纹的拓展，使能量能够更加集中于压头下方的局部岩石块体，有利于形成“八”字形贯通裂纹，促进岩石的破碎；随着槽深增加，压头下方岩石内部的应力状态和力学响应分区逐渐过渡改变。槽深较大时，压头下方的力学响应区域在原有裂纹扩展区、弹性区之间增加了破坏过渡区，该区域内微裂纹被压密，区域内岩石存在较大变形，但未出现明显破坏；切槽后，滚刀压头下方的岩体破坏机制由无切槽试样挤压剪切为主导的径向裂纹拓展，演变为由刀具和切槽共同控制作用—拉伸剪切为主导的主裂纹扩展。

Influence of pre-cutting groove on rock breaking mechanism of tunnel boring machine disc cutter

The emergence of rock breaking technology combined with high-pressure water jet and mechanical disc cutter has changed the operation mode of traditional tunnel boring machine (TBM). The research object is the rock-breaking mechanism of the high pressure water jet cutting grooves into the rock mass on both sides of the disc cutter. We carry out tests and numerical simulations of white sandstone slab samples with constant cross-section indenters penetrating into different pre-cutting groove depths. We use the DIC method to analyze the post-fracture images. The results show that: (1) The existence of the cutting groove blocks the expansion of the penetration crack of the indenter, so that the energy can be more concentrated on the local rock block, which is conducive to the formation of the splayed cracks and promotes the fracture of the rock. (2) With the increase of groove depth, the stress state and mechanical response zones inside the rock under the indenter are changed gradually. When the groove is deep, the mechanical response zone under the indenter further presents a failure transition zone, which locates between the original crack propagation zone and the elastic zone. In this area, micro-cracks are compacted, and the sample shows obvious deformation, but no obvious failures. (3) The use of grooving changes the rock failure mechanism under the indenter. Without grooving, the mechanism shows the radial crack growth dominated by extrusion shear of the complete specimen, whereas after grooving, it shows the main crack propagation that dominated by tensile shear controlled by both the indenter and the grooves.