Effects of Elevated Temperature and Pore Pressure on the Mechanical Behavior of Bullfrog Tuff

摘要

Samples of the Bullfrog Member of the Crater Flat Tuff from the depth interval 758.9 to 759.2 m in hole USW-G1 on the Nevada Test Site were tested in triaxial compression. Test conditions were: (1) effective confining pressure to 20 MPa; (2) temperature of 200 exp 0 C; (3) both dry and with pore water pressures from 3.4 to 5 MPa; and (4) a strain-rate of 10 exp -4 /s. The results suggest that the presence of water causes the strength to decrease. In addition, the brittle-ductile transition pressure for this rock was found to be about 15 MPa, regardless of saturation. Below this pressure deformation is characterized by unstable stress drops and the development of a single fracture, and above this pressure deformation is stable and distributed more uniformly throughout the sample. (ERA citation 07:049386)