Study On Three-dimensional Stress Specimens Of Cavern Rock Burst Simulation Test

Rock burst is a nonlinear dynamic destroying phenomenon in the underground engineering geological disasters.Due to the complexity of the problem,we fail to form mature theories and methods.In this paper,using the model test system of rock burst and the related monitoring methods,simulate the three-dimensional stress state large specimens of the standard test method for underground excavation rock burst and carry out indoor experiment of different loading methods for model specimens with two sections of circular cavity and straight wall,in turn detailed analysis the internal strain of specimens,chambers of the macroscopic damage phenomena,the rock burst severity,AE energy characteristic parameters and sonic rate test results,in order to further study the rules and mechanisms of generating the rock burst.Work content and conclusions are:(1)Under indoor laboratory conditions,use the pre opening ways to produce large-size model specimen.And use the rock testing machine to measure the uniaxial compressive strength of the same batch specimens.Get the load stress path of large-size specimens.(2)According to the model test results of two kinds of different sections,it can be seen that the internal strain variation law of the specimen is basically symmetrical.Under the stress loading path,the damage range of the circular cavity rock burst zone is 0.5a(a is the cavity radius).The scope of the damage zone of the straight wall vault is basically the same as the circular cavity.Under the condition that the compressive failure zone of the circular cavity,which is not placed at the top of the steel plate,is close to the periphery of the chamber,and the main direction is inclined to shear failure.Under the condition of the top placed steel plate,the straight wall arch roof is equivalent to the increase of the thickness of the overlying layer.The sequence of rock burst failure is the first side wall and the rear arch shoulder direction.The circumferential strain is the main reason for the crack and rapid expansion of the surrounding rock.(3)The four groups of rock burst model specimens were subjected to hydraulic and gas-liquid composite loading according to the determined stress loading paths.The model specimens with gas liquid composite loading are significantly higher than the hydraulic loading specimens at the corresponding failure point.The maximum amplitude,the maximum release energy and the number of AE events before and after the rock burst are also significantly higher than those of the hydraulic loading test.The macroscopic failure process and phenomena of the chamber rock burst are more obvious,and the degree of rock burst is more severe.(4)The sound wave velocity of the specimen before and after loading is tested by the sound wave test instrument.The results show that the complete destruction of the surrounding area is about 0.5a(a),which is consistent with the internal strain deformation analysis and the macroscopic failure phenomena.