EXPERIMENTAL STUDY ON ROCKBURST PROCESSES OF LIMESTONE UNDER UNLOADING CONDITION IN DEEP ROADWAYS

摘要

The characteristics of rock failure under unloading condition are different from those under loading condition. Unloading confining pressure experiments are conducted to simulate the failure process of stress released during underground excavation. The deformation features, mechanical parameters and failure characteristics were obtained based on the results of triaxial unloading tests of limestone. Results show that strain energy stored in rock is large enough to cause rock failure when it is released. Rock will outburst when the maximum in situ stress is excessively greater than the uniaxial comprcssivc strength of rock. In order to prevent the occurrence of rockburst, one of the basic methods is to release the strain energy in rock before excavation. Accordingly, the rock will not have a large amount of energy released to cause failure. In addition, rockburst can also be controlled or released by lowering the excavation speed or applying precautionary measures to control the displacement of surrounding rocks.