In an underground limestone mine recently developed, the stress changes in rock around the primary opening, which were induced by excavation of the secondary openings above or below the primary opening, are being monitored by means of pressure capsule. The floor displacement induced are also being measured by a special displacement meter coupling a laser beam and two solar batteries. Initial rock stress state and a tangential stress state at the primary opening were measured by double fracturing technique and stress compensation technique using lune-shaped flatjack, respectively. Furthermore, induced change of a pillar stress was predicted numerically.
The paper describes the outline of the excavation process, the measurement systems and the measured results which are compared with the predicted stress change with respect to excavation progress.