Publications Details
Measuring the dynamic compression and release behavior of rocks associated with HYDROPLUS (Part 2)
Three sets of rock samples have been subjected to planar impact to characterize loading, Hugoniot and release responses. A slate form Pennsylvania was tested over the stress range of 5 GPa to 140 GPa. Phyllite from the Lupin Mine (Canada) was tested over the 14--50 GPa stress region. Finally, granite samples from the SHIST test site (New Mexico) were tested over the 10--20 GPa stress region. The granite tests included a transmitted-wave experiment at about 10 GPa. In 12 of the 13 tests, a reverse-ballistic configuration (optimized for Hugoniot and release measurements) was used. The remaining test (conducted on the granite) provided a transmitted waveform from which precursor, Hugoniot and release properties were obtained. Velocity interferometry (VISAR) was used as the primary diagnostic throughout. The slate data showed an unexpected inflection downward in the Hugoniot at around 8 GPa. The slate and granite showed release paths lying below the Hugoniot for lower stress levels (below {approx} 60 GPa), while the slate release paths were ``normal`` (above the Hugoniot) at higher stress levels. In addition, the granite releases were found to lie substantially below the Hugoniot in the 30--40 GPa region; this may be related to the quartz-stishovite transition. The present results are generally consistent with earlier work.