Fractured Rock Permeability as a Function of Temperature and Confining Pressure

摘要

Triaxial compression tests were carried out on Shikotsu welded tuff, Kimachi sandstone, and Inada granite under confining pressures of 1–15 MPa at 295 and 353 K. The permeability of the tuff declined monotonically with axial compression. The post-compression permeability became smaller than that before axial compression. The permeability of Kimachi sandstone and Inada granite declined at first, then began to increase before the peak load, and showed values that were almost constant in the residual strength state. The post-compression permeability of Kimachi sandstone was higher than that before axial compression under low confining pressures, but lower under higher confining pressures. On the other hand, the permeability of Inada granite was higher than that before axial compression regardless of the confining pressure values. For the all rock types, the post-compression permeability at 353 K was lower than at 295 K and the influence of the confining pressure was less at 353 K than at 295 K. The above temperature effects were observed apparently for Inada granite, only the latter effect was apparent for Shikotsu welded tuff, and they were not so obvious for Kimachi sandstone. The mechanisms causing the variation in rock permeability and sealability of underground openings were discussed.