On the Elasticity and Strength-constants of Japanese Rocks

Abstract

This paper contains a description of experiments made for the purpose of determining the different moduli of elasticity, and the strength against rupture and crushing of some of the more common Japanese rocks. One main object of the experiments was to obtain data for the calculation of the theoretical velocity of propagation of earthquake-waves, and by comparison of this velocity with the results of observation, to gain some idea of the degree of continuity in the strata. The experiments on the moduli and the rupturing strength were performed on round columns of the rock about 4 centimetres in diameter and 60 centimetres long; those on strength against crushing were for the most part made on round columns 4 centimetres in diameter and 12 centimetres long. The Young's modulus of elasticity was calculated from the results of experiments on cross bending, the columns being supported at both ends. The modulus of rigidity was calculated from the results of experiments on the torsion produced by the application of measured twisting motives. The bulk-modulus was calculated from the known relation between it and the Young's and rigidity-moduli. The modulus of rupture was found by observing the load required to rupture the column by cross bending. The experiments on crushing were performed by means of a Bramah's press, the pressure being estimated by means of a Bourdon's gauge. The following Table (p. 140) gives the results of the experiments; the headings of the different columns sufficiently explain their contents.