抄録
The Permeability of the Shirahama sandstone was measured as a function of three principal stresses. A transient pulse method was used to measure the permeability. Permeability was determined from measurements of the decay of a small step change of pore pressure imposed at maximum stress direction. The measurements were made with increasing intermediate stress as well as with increasing maximum stress under constant minimum stress of 5 MPa, 10 MPa, 15 MPa, 20 MPa. Permeability changes due to maximum stress were dominant than those due to intermediate stress. Blue dyed epoxy impregnated thin sections of intact and stressed Shirahama sandstone were prepared to clarify pore structure change. Using an image processing technique, porosity, orientation and aspect ratio of pores can be estimated. Permeability decrease due to increase of three principal stresses can be interpreted in terms of the closure of preexisting pores with low aspect ratio and long perimeter.
