Development and application of multi-field coupling test system for deep coal-rock dynamic disaster

At present，the academic community has not yet been able to condense the applicable conditions of the unified rock burst inoculation mechanism. Through the self-developed multi field coupling test system for deep coal and rock dynamic disasters，the“stress-temperature-seepage-disturbance” multi physical field coupling analysis method is applied to the study of the influencing factors of rock burst. The single physical field(uniaxial test and conventional triaxial test) and the double physical field(confining pressure-seepage and confining pressure-disturbance) comparative test. This not only verifies the reliability of the self-developed equipment，but also provides a strong theoretical basis for the accurate picking and reliable identification of the induced factors of rock burst under multi physical fields. The test results show that：(1) The multi-field coupling test system of deep coal-rock dynamic disaster can carry out uniaxial and triaxial compression tests，cyclic loading and unloading tests and permeability tests under three-way coupling conditions under normal temperature，high temperature environment and low frequency dynamic disturbance. It can meet the test requirements of different engineering rock masses under complex stress paths and the test results are reliable. (2) The energy index in the loading process is analyzed by the multi-field coupling test of related dynamic disturbance to characterize the damage process of coal samples. It is found that when the confining pressure of coal sample is increased from 0 MPa to 4 MPa，the average peak strength is 14.75 MPa and 62.67 MPa respectively. The cumulative energy of single physical field is 24.3×10⁵ mV·ms，and the cumulative energy of double physical field is 52.0×10⁵ mV·ms. This further indicates that the disturbance strengthens the strength of the coal body and aggravates the degree of damage. (3) The failure types of coal samples are divided by<italic> RA</italic>/<italic>AF</italic> index. It is found that the complexity of different physical field failure types is aggravated under triaxial stress conditions，and shear failure is still dominant. This intuitively shows that the strength of coal samples in different physical fields is obviously affected by confining pressure. The overall performance is that the discreteness of monitoring data under multi-field coupling is significantly increased. (4) Because the real occurrence environment of the site is a multi-action mode of superposition of dynamics，statics and seepage mechanics，which aggravates the difficulty of prevention and control. The above analysis results are of great significance for further establishing the prevention and control system of rock burst under complex stress conditions.