Permeability variation during deformation and failure in triaxial test was considered for Shikotsu welded tuff. Pure water saturated cylindrical test specimens of 30 mm in diameter and length of 60 mm with constant flow rate method at 0.3 ml/min was introduced for compression, with strain rate of 10-5 s–1 on the consolidated samples under 1 MPa, 5 MPa, 10 MPa and 15 MPa for 24 hours until the axial strain reached at 10% in 22°C and 80°C. Permeability at the end of 15 MPa consolidation was lower than those of under 1–10 MPa. In compression
permeability basically decreased with slight disturbances around peak load points due to rapid volumetric change
under 1 MPa the permeability was larger, compare to 5–15 MPa confining pressure at 22°C
no apparent confining pressure dependency was observed at 80°C.
The permeability was lower at 80°C than 22°C. However, more water flow is expected for the same pore pressure gradient at 80°C due to lower viscosity of water.