Plane-strain model tests on rock-burst of horseshoe section caverns in hard and brittle rockmass

In order to discuss process and mechanism of rock-burst in the surrounding rock of horseshoe section caverns,a physical model,800 mm long and 800 mm wide and 200 mm thick with a horseshoe section cavern,was produced with hard brittle physical model materials from orthogonal experiments by the generalized indexes of uniaxial compressive strength(σc),brittleness coefficient(K) and exponential of strike energy(WB).The physical model was tested in the large triaxial model-test machine of geotechnical engineering under the high stress and plane strain condition.It was shown that a rock-burst which was paroxysmal in hard and brittle surrounding rock of horseshoe section cavern occurred during a transitory time in a limited loading-zone under the high stress condition when crack appeared,and that a relatively steady period appeared during relatively long time and a relatively broad loading-zone appeared after the rock-burst,following stress adjusting.The results of physical simulation were basically consistent with the actual engineering situation.