Comparison Test Of The Gradient Loading Rock Burst Model Of Hydraulic And Gas-liquid Composite Loading

Based on the improved gas-liquid composite rock burst model test device,the comparison tests of gradient loaded rock burst models was determined under different initial storage gas pressure conditions,the macroscopic damage characteristics,internal stresses and deformations,and the dynamic strain and acoustic emission characteristics of the failure process is analyzed systematically.The main research results are as follows.(1)The rock burst model test was performed using gypsum which is a similar material with good brittleness and brittleness.By comparing the failure phenomena of three specimens under different initial storage gas pressures,different initial storage gas pressures affect the energy concentration,dissipation and the rate of release of energy during destruction in the loading process of the specimens.The greater the gas pressure initially stored in the energy storage chamber of the gas-liquid composite loader,the greater the strain value and the shorter the destruction duration during failure of the specimen.Compared with hydraulic loading,the gas-liquid composite loading has less energy to be dissipated before the destruction of the specimen,and more kinetic energy of debris is converted during destruction,which promotes the occurrence and intensity of the rock burst.(2)When the vertical stress?_?(tangential stress)at the top is within the range of?_?/R_c=0.7~0.8,the three groups of specimens is damaged,which is basically consistent with the measured results when the rock mass was destroyed in the actual project.The model test of dynamic and static combined loading under gradient load is basically similar to the stress environment of actual engineering rock mass.(3)With the gas-liquid composite test specimen,the acoustic emission energy and the ring-counting parameters are far greater than the hydraulically-loaded specimens.The initial storage gas pressures ensures the energy release rate,make up for the lack of energy for static load.The damage is even more intense and make the specimen damage more violent.(4)The measured stress value curve of the internal stress sensor of the specimen shows that with the different position of the sensor,the measured value of the stress is decreasingly distributed from the upper part to the lower part of the specimen,indicating that the lateral friction force of the specimen weakens the downward transfer of stress.During the test process,there is a large impact on the location of the rock burst.The maximum release channel for the acoustic emission energy and ring count the ring count are located in the upper middle range of the three specimens.(5)By comparing the dynamic strain difference of the three groups of specimens,the size of the initial energy storage gas pressure determines the strain magnitude and strain gradient at the moment of failure of the specimen.The greater the initial energy storage gas pressure,the greater the dynamic strain at the moment of failure of the specimen and the more violent the rock burst failure.