Effect of frequency on Young's modulus and seismic wave attenuation

摘要

Laboratory experiments were performed to measure the effect of frequency, water-saturation, and strain amplitude on Young's modulus and seismic wave attenuation on rock cores recovered on or near the site of a potential nuclear waste repository at Yucca Mountain, Nevada. The purpose of this investigation is to perform the measurements using four techniques: cyclic loading, waveform inversion, resonant bar, and ultrasonic velocity. The measurements ranged in frequency between 10(sup (minus)2) and 10(sup 6) Hz. For the dry specimens Young's modulus and attenuation were independent of frequency; that is, all four techniques yielded nearly the same values for modulus and attenuation. For saturated specimens, a frequency dependence for both Young's modulus and attenuation was observed. In general, saturation reduced Young's modulus and increased seismic wave attenuation. The effect of strain amplitude on Young's modulus and attenuation was measured using the cyclic loading technique at a frequency of 10(sup (minus)1) Hz. The effect of strain amplitude in all cases was small. For some rocks, such as the potential repository horizon of the Topopah Spring Member tuff (TSw2), the effect of strain amplitude on both attenuation and modulus was minimal.