Penetrating granite specimens with different wedge cutters by changed RMT-150C system which is specially produced for indentation

and using DISP acoustic emission location system to research rock damage and physical deterioration. Acoustic emission test is an effective method to study the microscopic mechanism of rock fragmentation by tunnel boring machine (TBM) cutters. Testing results show that: rock breaking is the macro-phenomenon of internal microcrack’s initiation and development. There is a realistic corresponding trend of load value and AE signals when wedge cutters penetrate specimens at a uniform velocity. Load-penetration curve could demonstrate the process of specimen damage. Acoustic emission plane location results show that: there is a damage core under the dense broken core

which is clustered by micro-seismic locations and is seriously deteriorated. Damage core plays a significant role to produce the next dense broken core. Experimental results provide an explanation for the macro- phenomenon of rock breaking under TBM cutter. Blunt cutter’s indentation produces a damage core of spherical shape while sharp cutter’s water-drop shape. Blunt cutters are better than sharp cutters to break rock specimens because of deeper penetration and wider width of damage core.