圧裂法による岩石の引張強さに関する統計学的研究

概要

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In rocks the tensile strength S_0 is often substituted by the tensile stress S_t at the diameter of a cylindrical specimen which is weighted with a breaking load in the direction of the diameter, but in that case S_t is not always equal to S_0. The experiments by the present writer,as well as by other investigators, show the result of S_t>S_0 in some rocks, and in others S_t<S_0. To the distribution of the two strengths, the present writer applied the theory of the probability of minimum value of the strength of Griffith cracks. The theoretical ratio of the mean values of the two strengths is given as the function of the coefficient of uniformity m. And it is found that one of the chief causes for S_t>S_0 is the distribution of Griffith cracks in a rock specimen. But there are other causes also, namely, the existence of compressive stress, the crush at the loaded end of the diameter, etc., by whose combined effects is brought about the relativity of S_t and S_0 . Accordingly, in order to estimate the mean tensile strength S_0 in rocks, it would be more suitable to use the value obtained by the statistical treatment of the bending strength rather than to use S_t.
社団法人日本材料学会の論文
1960-06-15