When constructing underground caverns, it is important to estimate the damaged zone around rock caverns caused by excavation. In situ experiment were conducted to investigate the crack growth into rock mass by acoustic emission (AE) measurement.
The measurement was carried out in Kamaishi mine of Iwate Prefecture. The following conclusions are obtained: (1) AE activities decrease gradually with the time progress after blasting, (2) both tensile cracks and shear cracks occurs intensively around a rock cavern, (3) the damaged zone generated by digging grows up to the wider domain where the excavation has not yet reached, (4) the types of blasting do affect the damaged zone generated.