2025 Volume 81 Issue 9 Article ID: 24-00272
The influence of the setting of measurement criteria on the results of laboratory elastic wave measurement of improved soil specimen were examined using a test apparatus in which the specimen was crimped between the oscillator and receiver. The test results were compared with those of previous studies. The required clamping pressure was evaluated to be 20 kN/m2 to minimize the influence of the housing of the vibrating element and the crimping of the specimen in this test apparatus. At this fixed pressure, the elastic wave velocity of the specimen with a length-to-diameter ratio of 2.0 became less dependent on the frequency of the input and/or received wave in the input wave frequency range of 10~50 kHz. In other words, in this frequency band, the effect of velocity dispersion or near-field is estimated to be small, and a convergence trend was recognized in the correlation between P- or S-wave velocities and unconfined compression strength. In addition, when the correlation of S-wave velocity was compared with previous studies, S-wave velocity for the same unconfined compression strength was different, but the increasing gradient was the same. The factor that caused the difference was presumably the influence of the measurement criteria (i.e., clamping pressure setting or wavelength) based on the experimental results of this study.
