Dynamic properties of rock required for prediction calculations

Dynamic loading and unloading curves were measured to 29 kbar in wet and dry tuff from the Nevada Test Site, wet and dry sandstone from the mixed company site, and wet soil from the Essex site (in Louisiana). The curves were obtained using multiple embedded gages that recorded particle velocity and/or stress histories at up to four different depths in gas gun impact experiments. The Fowles - Williams method was used to generate compression and release paths from these records. In dry tuff at low pressures, the stress wave is quite dispersive, and at higher pressures, it is much less so. Yielding occurs at about one kbar in dry tuff and at about four kbar in dry sandstone. Dispersion, yielding, and permanent compaction were less evident in the experiments with water-saturated sandstone. In the Essex soil experiments, the main feature observed was the amount of permanent compaction, which reflects the degree of water saturation. No indication of precursor was seen in this low-strength material.