大理石と方解石の圧縮強度に関する研究 (第1報)

Abstract

Uni-axial, bi-axial and confined compression tests were performed on Akiyoshi Marble. Specimens were unloaded on several stages of these experiments, and optical micro-scopic observations were performed about thin sections made from these specimens. On the other hand, uni-axial compressive test was also performed on calcite specimens.Based on these experimental results, some considerations about strength failure of these materials were discussed and following conclusions were obtained.1) The fracture behavior of calcite was anisotropic. In c-axis direction it behaved as brittle, on the other hand in a-axis direction it behaved as elasto-plastic. And, the strength failure and yielding point was about 1500 and 40kg/cm2 respectively.2) The linearity at low stress level and non-linearity at high stress level of the stress-strain relation of marble could be explained by the mobilization of the hindered cleavage sliding of calcite grain due to micro-crackings surrounding the grain.3) The extended Von Mises fracture criterion well explained experimental results qualitatively, but quantitatively insufficient.4) The anisotropy of lateral strain under bi-axial compression could be explained by the directional development of cracking from pre-existent cracks.5) The formation of ultimate failure plane did not correspond to the point of strength failure, but rather corresponded to the rapid stress drop after the strength failure.