花こう岩の強度試験における試験片の数について
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概要
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Specimens of 161 cylinders (30φ×60mm) and 113 circular disk (30φ×15mm) were prepared from a granite block. On these specimens, compressive and tensile strength of granite were measured by means of conventional compression and radial compression (Brazilian) test methods.All the data of the compressive strength were randomly devided into 32 groups, each of which was including 5 measurements. And also, all the data of the tensile strength were randomely grouped into 22 groups, each of which was including 5 measurements. On each group, the mean strength, the square-root of unbiased variance, and the 95% confidence limits of the mean strength were calculated. All the data were rearranged and were randomly devided into 16 groups for compressive strength and 11 groups for tensile strength, each of which was including 10 measurements. The calculation of the statistical values was also carried out for each.Increasing the number of specimens included in a group until the total number of 161 was reached for compressive strength, and the total number of 113 was reached for the tensile strength, the same process as above was repeated and the statistical values of each group were calculated.The values of mean strength, square-root of unbiased variance, and 95% confidence limits were plotted on graphs to the number of specimens included in a group.While the permissible differences to the total mean strength (1662kg/cm^2 for the compressive strength and 104.4kg/cm^2 for the tensile strength) were decided as the percentage deviation to the total mean strength.And then, the values of 95% confidence limits of the mean strength calculated above were compared with the permissible differences. Thus the number of specimens required to obtain mean compressive and tensile strength of granite which are within 15% to its true mean strength with 95% accuracy (it is assumed that the true compressive and tensile strength of granite is the mean value of the compressive strength of 161 specimens and the tensile strength 113 specimens of measured).
- 社団法人日本材料学会の論文
- 1967-01-15