Experimental study on acoustic emission characteristics of jointed rock mass by double disc cutter

Abstract

The characteristics of joints are crucial factors which influence the penetration efficiency of tunnel boring machine (TBM). Based on the theoretical study, numerical simulation and experimental research, many researchers have studied the interaction between TBM disc cutters and jointed rock mass. However, in most of these works, the effect of joint on rock fragmentation by double disc cutter has been scarcely investigated. Thus, the effects of joint orientation and joint space on rock fragmentation by double disc cutter are highlighted in this study. During the test, jointed concrete specimens are adopted to simulate jointed rock mass. Improved RYL-600 rock shear rheological instrument was employed during the indentation process under disc cutters, and acoustic emission location system was used to analyze the rock damage and physical deterioration. The results show that there are four failure modes and three modes of crack initiation and propagation in jointed rock mass. It is concluded that the existing joint planes have obviously restrained the crack initiation and propagation during the rock fragmentation process. The results also indicate that samples are damaged most seriously when joint orientation equals 60°, which is proved to be the optimum joint orientation in TBM penetration.

摘要

节理倾角和间距是影响全断面隧道掘进机(TBM)破岩效率的重要因素。 到目前为止, 许多学者基于理论研究、 数值模拟和实验, 研究了节理对滚刀破岩的影响。 然而, 在多数研究中, 节理对双刃盘形滚刀破岩的影响却很少。 因此, 本文重点研究了节理倾角和间距对双刃盘形滚刀破岩效率的影响。 通过改装 RYL-600 岩石剪切流变仪, 采用预制节理水泥砂浆试件模拟节理岩体, 利用声发射测试系统进行声发射的定位特征分析, 研究节理岩体在双刃盘形滚刀作用下岩石破坏的全过程。 试验结果表明: 节理岩体有 4 种破坏模式和 3 种裂纹扩展形式; 在岩石破坏过程中, 节理对裂纹的扩展有明显的控制作用; 在节理倾角为 60°时试样破坏最严重, 进一步验证了滚刀破岩的最优角是60°。