Abstract
We monitored AE (Acoustic Emission) in the frequency range from 5 to 100kHz in a porphyrite around an underground powerhouse, measuring 24.0m wide, 46.6m high and 134.5m long at 280m below the surface. Eight AE events could be located and their fault plane solutions were obtained from P-wave radiation pattern. The solutions are consistent with a strike and a dip of the most dominant joint surface, in situ stress state, and displacements measured by a multi-extensometer. These results indicate that fault plane solutions can be applied to assess stability of underground powerhouses excavated at relatively shallow depths, in a similar way to deep mines where the method has been practically used.
