Thermomechanical damage recovery parameters for rocksalt from the Waste Isolation Pilot Plant
- RE/SPEC, Inc., Rapid City, SD (United States)
Laboratory tests were conducted in which intact WIPP salt specimens were damaged by testing under constant strain-rate triaxial conditions at low confining pressure (0.5 MPa) and near room temperature (25{degrees}C) until 1.5 percent axial strain was reached. Introduction of dilatant damage caused specimen volume to increase and compressional wave velocities and amplitudes to decrease. Specimens were then subjected to hydrostatic loads of 15 MPa at a temperature of either 20{degrees}C, 46{degrees}C, or 70{degrees}C. Under these conditions damage was partially recovered and specimen volume and compressional wave characteristics approached the values of the undamaged state. The data from each test were fitted using a first order kinetics law to determine characteristic time constants for the damage recovery process at each temperature. The mean time constant associated with recovery of ultrasonic amplitudes decreased as temperature increased, as expected for a thermally activated process. Time constants associated with ultrasonic velocities and with volumetric strains showed no systematic change with temperature. The modeling results show that time constants are very short compared with time scales required for creep closure of rooms and shafts, implying that the rate of healing under confining pressure will be extremely rapid. The rates of volumetric strain recovery determined at different temperatures were fitted to an Arrhenius plot to determine an activation energy for the recovery process. The data were fitted using linear least squares to calculate an activation energy of 10.5 kJ {center_dot} mole{sup {minus}1}.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 105697
- Report Number(s):
- SAND-93-7111; ON: DE95017546; TRN: 95:020569
- Resource Relation:
- Other Information: PBD: Aug 1995
- Country of Publication:
- United States
- Language:
- English
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