In this study, a new method was examined that used acoustic emission (AE) monitoring
data, in combination with a primary Boundary Element stress analysis, to back-calculate
rock mass strength. The presented AE data came from the National Radioactive Waste
Repository (NRWR) for low- and intermediate-level waste (LLW/ILW). AE monitoring is
able to detect the pre-peak, peak, and post-peak stress changes in rock mass. The
presented method used AE monitoring data to back-calculate parameters, such as uniaxial
compressive strength and the rock mass deformation modulus. The AE initiation threshold
was used to develop an objective function that considered the stress in the rock mass
and the rock mass strength. The findings of this research propose that most AE events
can be related to the crack initiation threshold, and in space, most of them are located
at points away from the excavated walls. In the vicinity of the excavation damage
zones around the cavities, the stress conditions beyond the crack damage boundary
of the rock mass occur in many areas, leading to significant irreversible deformations.
This novel method was demonstrated to aid in the prediction of rock mass strength
and is a valuable, non-invasive method for improving the spatial prediction of rock
mass parameters, which will lead to safer underground storage facilities.
