Experimental study on law of limit storage energy of rock under different confining pressures

摘要

To investigate the effects of different unloading rates on rockbursts, the conventional triaxial compression tests and confining pressure unloading tests have been conducted on rock samples. The variation law of stress and stress thresholds for structural failure of rock sample under different confining pressures was analyzed, and the influence of different unloading confining pressure rates on limit storage energy during rock sample failure process was revealed. Experimental results showed that under uniaxial compression, the stress for structural failure of the rock sample is the same as stress thresholds for structural failure. In the conventional triaxial test, the stresses for structural failure and stress thresholds for structural failure of the rock sample will increase with the increase of confining pressure. Compared with the stresses for structural failure, the stress threshold for structural failure of rock samples increases by 32.88%, 53.63%, and 78.51%, respectively when the confining pressures are 10 MPa, 20 MPa, and 30 MPa. Under different confining pressure unloading rates, the limit storage energy of samples is also different. The higher the confining pressure unloading rate is, the smaller the limit storage energy is. When confining pressure increases, the limit storage energy of rock samples increases. Under the same initial confining pressure and confining pressure unloading rate, the change of axial pressure has little effect on the limited storage energy of rock, i.e., the energy required for rock failure is a definite value under certain conditions and is not affected by the stress loading path. This research can be helpful to understand and assess the rockburst during the deep rock mass excavation by different tunneling methods.