ねじり試験による岩石の剛性率の測定

抄録

In this paper, the authors report a testing method of torsion of rock substance. The test piece for the torsion test is prepared by the following procedure. A boring core of rock sample is glued to steel end-pieces by means of an alignment jig. As drying out thl glue, the section of rock cylinder is reduced by 20-30% over three quaters of its length using the grinding lathe, so that the centre line of the reduced section (effective section) of rock cylinder might coincide the centre line of the steel end-pieces. This procedure is applied to furnish the test piece for the uniaxial tension test of rock substance.
The angle of torsion is measured with the double mirrors double reflecting type optical lever, the advantage of which is the insensivity to the rotation of the test piece.
The modulus of rigidity measured by the torsion test mentioned above is compared with ones calculated from Young's modulus and Poisson's ratio measured by the uniaxial compression and tension test. It is revealed that the modulus of rigidity obtained from the torsion test is smaller than one obtained from the uniaxial compression test and greater than one obtained from the uniaxial tension test.