Measurements of Velocity Variation of Rock Samples under Uniaxial Stress by a Modified Transmission Method

An improved method of measuring in-situ stress, which is based on the anisotropic behavior of sound wave velocity, was presented. In the method, veloc-ities must be measured as a function of stress on one side plane of a rock body. This kind of measurements causes some problem that the transmission efficiency of P-wave which is the best indicator of stress is low, meaning that the velocity variation for the other type of waves has to be measured and it might not be noticeable. To examine this problem, four devices are developed. Then, using them we measured the velocity variations of rock samples under uniaxial stresses in the way stipulated by this method. The measurements show that the velocity variation can be clearly detected though the type of the wave was not identified. 1