In order to comprehensively reveal the long-term creep failure mechanism of coal rock,the long-term uniaxial compression graded creep acoustic emission test of coal rock was carried out,and the creep deformation and acoustic emission laws of coal rock under different stress levels were analyzed.On this basis,the critical power-law catastrophe function was introduced into the ideal viscoelastic-plas-tic body which was connected in series with the Burgers body to establish the coal rock catastrophic creep model.The research results show that the uniaxial creep of coal rock goes through three stages:deceleration,stability and acceleration creep,and the variation of acoustic emission parameters under different stress levels can well reflect the three stage deformation characteristics of coal rock creep.In the deceleration creep stage,the acoustic emission events are more active.In the stable creep stage,the acoustic emission activity at low stress level is more than that at medium stress level.When transitio-ning from the stable creep stage to the accelerated creep stage,the coal rock suddenly undergoes mac-roscopic brittle failure,the strain changes abruptly,and the acoustic emission suddenly increases,pres-enting the characteristics of catastrophic failure.During the deceleration and stable creep stages under high stress levels,the internal cracks of the coal rock are fully and uniformly developed,leading to the ultimate crushing catastrophic failure of the coal rock,which is different from the shear failure of uniax-ial compression failure.The established coal rock catastrophic creep model can fully reflect the deceler-ation,stability and acceleration creep stages of coal rock.Several nonlinear creep models have predic-ted the maximum correlation coefficient of high stress level creep test results to be 0.74,while the cor-relation coefficient predicted by the catastrophic creep model is greater than 0.97.The fitting results of rock creep test data show that the catastrophic model can well describe the creep process of all kinds of rocks,and the critical power-law index β plays a controlling role in the catastrophic failure.With the increasing of β,the rock creep also changes from progressive failure to catastrophic failure,thus verif-ying the correctness and applicability of the coal rock catastrophic creep model.
万方数据
维普
