VELA-UNIFORM DYNAMIC PROPERTIES OF ROCKS
STANFORD RESEARCH INST MENLO PARK CA POULTER LABS
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The goal of the present program is to measure some of the material properties under shock conditions in simple rocks and minerals. The pressure region of interest is the region in which the material strength of the rock affects the shock wave. The property that is measured is the Hugoniot equation of state. From measurements of this function, information is obtained about such aspects as phase transitions, elastic wave amplitudes and velocities, and pressure volume relations above the elastic limit. The measurements in the program also permit a comparison of the behavior of single crystals with the polycrystalline rock. Results indicate that 1 A two-wave front in the shock wave is recorded in each material. This is thought to be the result of failure at the elastic limit by either fracture or slip. A three-wave structure is sometimes recorded in the carbonates. The additional front is probably due to a phase transition. 2 There is a difference between the Hugonios of single crystals and polycrystalline rocks. Compared to the single crystals, there is a decrease in peak stress and velocity in the first wave of the polycrysalline rocks. This is greatest for the porous rocks and least for polycrystalline rocks with no porosity. The peak stress and velocity of the first wave depends strongly on porosity but it has not been demonstrated which parameters controlling porosity e.g., cementation, grain size, sorting, etc. are most important.
- Seismic Detection and Detectors