Study Of The Synchronized Correlation Between Stress And Ultrasonic Velocity Of Sandstone In Real Time

Aiming at the shortage of correlation study between rock ultrasonic velocity and stress state recently, this paper designed a cocurrent and simultaneous joint test technical of the ultrasonic velocity and stress for rock sample. The Neogene sandstone from the seventh water tunnel of Yintao water supply project was taken as research objects, and a research was carried out about the mechanical properties and the ultrasonic propagation characteristics of different stress states. Based on the test results, the characteristics of stress-strain and ultrasonic velocity were studied, and then the synchronized correlation between stress and ultrasonic velocity in real time was analyzed. This paper provided a reference for the rock mechanics theoretical research and rock stress measurement methods in engineering practice. The study results demonstrated:(1) There was good synchronization in the relationship between ultrasonic velocity and stress of sandstone, and the ultrasonic velocity had a good response for the change of stress and the destruction process in a variety of stress state.(2) The influence of stress was limited to a certain range, while the stress of sandstone exceeded a certain value, the change of stress no longer caused obvious change of ultrasonic velocity of the sample. In this paper, the change rule of the sandstone ultrasonic velocity with stress variation was discussed. The relationship between ultrasonic velocity and stress was linear correlativity, and the fitting formula had been got.(3) The ultrasonic velocity of sample had a more sensitive response to the initial load of stress, which caused a rapid pace of change and a lower initial value of ultrasonic velocity. While during the repeated loading after initial loading, the change of ultrasonic velocity slowed down significantly, and the initial value of the ultrasonic velocity improved. The unloading process gave no obvious command over the relationship between the ultrasonic velocity and stress, which appeared stable during the repeatedly loading and unloading process. The loading and unloading speed had an effect on the change rate of the ultrasonic velocity, but no significant effect on the relationship between the ultrasonic velocity and stress.(4) The effect of confining pressure on the ultrasonic velocity was mainly reflected in the whole process of the monotonous conventional triaxial compression. As a result of the confining pressure, the axial stress of sample was still at a large level after yield failure, and the ultrasonic velocity maintain a high value. The confining pressure kept the stability of the structure of the sample, which led to the stability of the sample ultrasonic velocity.