Abstract
Physical properties including compressive strength, elastic wave velocities, deformation properties, characterristics on breaking surfaces, etc. were investigated on layered anisotropic rocks such as foliated sandstone, sandy shale, slate, schist, etc. as well as jointy granite.
These are summarized as follows.
1) Compressive strengths of layered rocks differ according to the inclination of compression with respect to the direction of layers, showing a concave curve with the minimum value at the inclination from 30°to 45°. The angles corresponding to the lowest strengths depend on the reference compressive strenghs obtained by the tests in which compressive stresses are applied at right angle to layers. Larger strengths correspond to the angle of 30°, while smaller strength to the angle of 45°.
2) Anisotropic factors for compressive strengths seem to be mainly governed by the stresses occurred at the time of formation of the strata.
3) Static young's modulus is also dependent on the inclination of the layers. The relation of the former to the latter is similar to that observed in compressive strengths.
4) Compressive strengths obtained perpendicular to layers are expressed as a linear function of anisotropic factors for wave velocities, such as y=ax.
5) Properties of isotropic rocks with anisotropic structures (joint, cracks, dikes) may well be explained from the view point of behaviors observed in layered rocks.
