Experimental Study On Acoustic Emission Of Rock Failure Under True Triaxial Stress

At present,the study of rock deformation and failure process is based on the conventional three axis stress state,but in the true three axis stress environment,the deformation and failure characteristics of underground engineering rock mass are different from the conventional three axis stress environment.Therefore,the study of the deformation and failure process of rock under the true three axis stress condition is of great theoretical significance and guiding value for revealing the mechanism of rock failure in underground engineering.In this paper,a series of true triaxial tests were performed on sandstone through a self-developed true triaxial testing system,which was combined with acoustic emission(AE)monitoring to systematically study the damage and failure behaviour of sandstone in different triaxial stress states.The main results are as follows:(1)A series of true triaxial loading experiments of sandstones were carried out using a self-developed true three-axis electro-hydraulic servo control system.The strength and deformation characteristics of the rock under true triaxial stress conditions were systematically studied,and the mechanism of the initial suppression and promotion of the deformation and destruction of rock by the intermediate principal stress is deeply revealed.(2)Based on the true triaxial test results of sandstones under different principal stresses,the variation law of acoustic emission characteristic parameters of sandstone during triaxial compression is analyzed,and the precursory characteristics of rock failure under true triaxial loading conditions are revealed.(3)Based on the principle of fractal reconstruction phase space,an associated fractal dimension model of rock acoustic emission parameters is established.The variation rule of the correlation dimension D of the acoustic emission number of rock under the influence of different intermediate principal stresses is systematically studied,and the fractal characteristics of rock acoustic emission parameters during true triaxial failure are revealed.(4)Using acoustic emission location technology,three-dimensional visualization of the distribution of rock microfracturing events was achieved.The three-dimensional spatial evolution model of infancy and development of internal microcracks in rock failure process was studied in depth,and reveals the spatial morphological characteristics and damage evolution of rock under true triaxial loading conditions.