Research On Stress Effect Of Mechanical Characteristics Of Sandstone

Based on united tests of loading and acoustic measurement, mechanical characteristics change law with stress is studied under different stress state because of the importance of mechanical characteristics of sandstone in engineering practice. The results will provide a reference for the rock mechanics theoretical research and rock mass stability evaluation in engineering practice. The conclusions are as follows:(1) Under static loading condition, plastic strain changing with stress presents the two-stages behavior:linear stage and exponent stage, so is plastic-elastic strain curve. Static modulus increases as stress increase before stress threshold and decreases as stress increase after stress threshold. Based on experimental data, empirical relationship between static modulus and stress is presented.(2) Under dynamic loading condition, the velocity of elastic wave in rock increases with the voids closing, so is stress. Taking void closing percentage as the bridge between stress and velocity, semi-empirical relationship between stress and velocity is presented.(3) Based on the united tests under cocurrent, simultaneous and same stress condition, both static modulus and dynamic modulus have the same variation tendency with stress. Static modulus and dynamic modulus increase with stress at the compression and elastic deformation stage, while decrease at the plastic deformation stage. The static elastic modulus and dynamic modulus show a good linear correlation.