含有水分による花商岩の縦波速度の変化と粒径および空隙形状との関係
1982 年 98 巻 1137 号 p. 1111-1116
詳細
1982 年 98 巻 1137 号 p. 1111-1116
Variation of longitudinal wave velocity with respect to water saturation was measured for twenty seven kinds of granites by ultrasonic pulse method at room temperature and atomospheric pressure, and therelationships among grain size, shape of pore and longitudinal wave velocity were investigated. Kuster's expressions for bulk and shear moduli were applied to estimate the shape of pore in granite.
The main results obtained are as follows:
1) The effect of water saturation on the longitudinal wave velocity is comparatively larger for granites than other types of rocks such as volcanic and sedimentary rocks. The velocity difference betweensaturated and dry states increases with increasing effective porosity, and does not depend on grain size.
2) The indices of granites, which mean the velocity change corresponding 1% effective porosity, indicate 0.87-3.48.The values of aspect ratio estimated based on the Kuster's expressions are 3.6-16.5×10-3. It is therefore assumed that the large indices are caused by the fact that the shape of pore in granite is in the form of cracks.
3) The values of aspect ratio of pores in granites are larger than those of crystalline limestones, and have no correlation with grain size. These facts suggest that the velocity difference in granite mainly depends on the effective porosity.
