Experimental Study of Multiple Physical Parameters Monitoring during Uniaxial Loading Process of Sandstone

Abstract

Aiming at the damage evolution and energy release characteristics of sandstone in failure process, uniaxial and cyclic loading experiments were conducted with the average temperature, infrared temperature field, acoustic emission (AE), and displacement field being monitored simultaneously. The results show that in the low stress stage, the initial pores and fissures are compressed and the thermoelastic effect is insignificant. At the same time, the AE events are active, but most of the events are released with low energy. Then, the surface of the specimen shows stratified displacement phenomenon in the vertical direction. In the following stage, the thermoelastic effect is significant, and the average temperature of specimens shows a linear correlation with stress, whereas the AE is relatively inactive, and vertical surface deformation shows further homogenization and saliency. Because of the top and bottom constraints, the horizontal displacement field shows axis symmetrical distribution of double half-ellipse like a drum. During the yielding phase and the rupture moment, the average temperature rises obviously because of the heat from the friction of the rupture surface, and the temperature field also appears the phenomenon of differentiation; in the meantime, a large amount of AE events occur and the proportion of high energy events increases; further, the deformation field is significantly gathered near the ruptured position. Finally, the time sequence of the multiple physical parameters (AE parameters, average temperature, temperature fields, horizontal and vertical displacement fields) is summarized, which can be a reference for the stress state and failure analysis.