Temperature-confining pressure coupling effects on the permeability of three rock types under triaxial compression

Abstract

Triaxial compression tests were carried out at 295K and 353K under confining pressure of 1-15 MPa for Shikotsu welded tuff, Kimachi sandstone and Inada granite. The samples were kept for 24 hr consolidation and then axial compression was applied measuring permeability. Permeability decreased monotonously for Shikotsu welded tuff. The permeability decreased first, began to increase before peak load and showed almost constant value in the residual strength state for Kimachi sandstone and Inada granite. Permeability decreased by failure for Shikotsu welded tuff. It increased due to failure under low confining pressures but decreased under high confining pressures for Kimachi sandstone. It increased due to failure for Inada granite. The permeability at 353K was lower than that at 295K for all of the three types of rock. The mechanisms of the permeability decrease are also shown.

Variation in the Permeability of Intact and Fractured Rocks due to Transient Disturbances in Axial Stress or Pore Pressure

“…e permeability decreased from k 2 to k 3 due to rock failure (Figure 17(a)), and this result is the same as those presented by Alam et al [15] for the same rock type. is reduction in permeability may be due to the crushing of the matrix that consists of volcanic glass (Figure 19(a)).…”

“…Figure 7. e permeability of this sandstone increased owing to the failure (observed in the variation in permeability in Hold-2 to Hold-3, Figure 6, or k 2 to k 3 , Figure 7) as was reported for the Kimachi sandstone, which is a neogene tu aceous sandstone in Japan [15]. is occurred although the axial stress disturbances caused the permeability values of the intact rocks (variation in permeability in Hold-1 to Hold-2, Figure 6, or k 1 to k 2 , Figure 8(a)) and fractured rocks (variation in permeability in Hold-3 to Hold-4, Figure 6, or k 3 to k 4 , Figure 9(a)) to decrease.…”