The ability to improve rock-breaking efficiency of tunnel boring machines in hard rock stratum is significant to improve driving speed and reduce construction cost and time. The undercutting method has been used to improve the rock-breaking efficiency of disc cutters, including the design of curved and multistage cutterheads. The limited radian of curved cutterheads and the number of multistage cutterheads, however, are restricted by the current manufacturing level. We explored mechanical response and rock-breaking efficiency assisted by water jet kerfs as the vertical free surface. We conducted a quasi-static penetration test of the disc cutter considering four kerf depths and three groups of confining pressures. We analysed the surface crack propagation and fractures inside the sample using acoustic emission and computed tomography scanning. We studied the influence of confining pressure and cutting depth of the water jet on penetration force, rock chips, and specific energy. We analysed the failure evolution and stress field of kerf specimens using numerical simulation. The results showed that increasing cutting depth relieved restraint stress and the resulting influence of the confining pressure on removed rock volumes and specific energy was not remarkable. We recommended a kerf depth of greater than 18 mm to reduce penetration force and significantly improve rock-breaking efficiency.

提高硬岩层隧道掘进机的破岩效率的能力对于提高行车速度，减少施工成本和时间具有重要意义。底切方法已被用于提高圆盘切割机的破岩效率，包括弯曲和多级切割头的设计。但是，弯曲刀头的弧度和多级刀头的数量受到当前制造水平的限制。我们探索了由水射流切缝作为垂直自由表面辅助的机械响应和破岩效率。考虑到四个切缝深度和三组围压，我们对圆盘切刀进行了准静态渗透测试。我们使用声发射和计算机断层扫描技术分析了样品内部的表面裂纹扩展和裂缝。我们研究了水射流的围压和切割深度对穿透力，碎石和比能的影响。我们使用数值模拟分析了切口切口的破坏演化和应力场。结果表明，增加切削深度可缓解约束应力，而围压对去除的岩石体积和比能的影响并不显着。我们建议切缝深度大于18毫米，以减小穿透力并显着提高碎石效率。结果表明，增加切削深度可缓解约束应力，而围压对去除的岩石体积和比能的影响并不显着。我们建议切缝深度大于18毫米，以减小穿透力并显着提高碎石效率。结果表明，增加切削深度可缓解约束应力，而围压对去除的岩石体积和比能的影响并不显着。我们建议切缝深度大于18毫米，以减小穿透力并显着提高碎石效率。