1975 年 16 巻 2 号 p. 63-74
Joint planes used in this experimental study consisted of three artificial joints of extension fractured surface (EFS), sawn-cut surface (SCS), and polished surface (PS).
Shearing experiment with test pieces about 60 mm in diameter were performed under normal stress σN from 0.2 to 120kg/cm2. The roughness of above three planes and natnral joints was measured by surface roughness meter (SE-0) as shown in Fig.2.
The relation between shearing strength τf and σN is shown in Figs. 4 and 5 for virgin shear of EFS, in Figs. 6 and 7 for repeated shear at first and second cycles of EFS, in Fig.9 for SCS, and in Figs.11 and 12 for PS.
Power law of friction may be suitable to express τf-σN relations (see Figs.8 and 10).
The dependence of frictional properties on normal stress is summarized in Fig. 13. From Fig. 13 the true frictional angle φu may be about 25°-26°.
Dilation angle dn° at peak shear stress has non-linier relation to secant frictional angle φs of tan-1 (τf/σN) in Fig.19, which showes, though widely scattered, an important relation between φs and dn. The effect of filling materials on frictional resistance of joint is summarized in Fig.21 according to surface roughness, particle size and moisture condition.
Weathering less than about 7% in porosity may be negligible effect on shear strength, but effective on deformation properties.