单轴加载条件下砂岩的波速与应力-应变相关性研究

he rock acoustic wave testing technique is an important means to study rock mechanics. It is easy to analyze many physical and mechanical parameters of rocks by acoustic wave testing data. But it is difficult to determine the quantitative corelationship between stress and ultrasonic velocity of rocks, especially for the soft sandstone. This paper selected 6 groups of specimen to study the qualitative and quantitative corelation between axial stress and ultrasonic velocity of soft sandstone under the condition of uniaxial complete compression process . The testing results showed that there is good synchronization in the corelation between ultrasonic velocity and axial stress and strain of sandstone, the sample wave velocity variation characteristics can be divided into 3 stages, namely wave velocity growth period, decreasing period and stable period. It is found out that the equation V=aσ+b may fit the relationship between ultrasonic velocity and axial stress in the front of growth period. The parameters of a and b values of the same kind of ultrasonic velocity with axial stress are approximately corresponding for the different samples. For the P wave, the parameters of a varies from 30 to 70, mainly about 50, the parameters of b varies from 2000 to 2400, mainly about 2300; but for the S wave, the parameters of a varies from 20 to 75, mainly about 30, the parameters of b varies from 1000 to 1400, mainly about 1300. On the whole the change speed of the S wave velocity with axial stress is slightly less than P wave velocity with axial stress