The study was started mainly to investigate horizontal velocity change and attenuation not only in pre-failure region but also in post-failure region. Beyond the strength failure point, ten rocks were tested in uniaxial compression and elastic-wave velocity and wave height in lateral direction were measured. Typically, the velocity and the wave height started decreasing at relatively low stress level in pre-failure region. The wave height decreased more rapidly than velocity; (Wave height change) / (Initial value of wave height) = 3 (Velocity change) / (Initial value of velocity). It was also found that the velocity and the wave height were correlated with the lateral strain which increased with crack number and length within a rock specimen.
The experimental results in compression were compared with those in tension which had been carried out by the authors, and two interesting findings were obtained. 1) At the strength failure point of Inada granite and Akiyoshi marble, the lateral strain in uniaxial compression test was close to that in uniaxial tension test. 2) Energy loss in a loading-unloading cycle in uniaxial tension test was compared with the attenuation of elastic wave in uniaxial compression test, and a good correlation was found between the two.
