Roadway excavation and mining underground coal mine is a process of unloading confining pressure. Compared with the conventional triaxial compression test

the coal rock showed different mechanical properties during unloading confining pressure. Based on two kinds of stress paths the conventional triaxial and unloading confining pressure tests

it is found that both the conventional triaxial or unloading confining pressure test

the coal sample caused by high confining pressure are greater strain and more intense failure. In the case of the same initial confining pressure

compared with the conventional triaxial test

unloading confining pressure tests peak secant modulus is smaller

secant Poisson’s ratio is larger; coal sample failure more intense when unloading confining pressure

the lateral strain is larger

and the axial strain but little difference. By unloading confining pressure effect coefficient analysis

it is found that the higher the initial confining pressure and the greater the rate of unloading confining pressure

the unloading confining pressure effect coefficient of coal sample is smaller

the more easily failure of coal sample

the secant modulus under high confining pressure decrease is consistent. Conventional triaxial and unloading confining pressure test failure process of energy change of anthracite analysis show that: the faster the rate of unloading confining pressure

the limit stored energy of coal samples is smaller

more easily instability and failure to verify the unloading confining pressure effect coefficient analysis results. In high confining pressure

coal sample failure requires more energy under conventional triaxial tests and unloading confining pressure test

reveal that higher confining pressure of coal sample

the stronger failure.