Progress and distribution of lateral displacement of rock specimen undre the triaxial compression test

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Triaxial compression tests were conducted for Akiyoshi marble, Shirahama sandstone and Berea sandstone to discuss about the progress and the distribution of lateral displacement of the specimens. The measurements were conducted at the center of the specimens by using twelve displacement meters of cantilever type mounted around the specimen in every 30 degrees. First, the measured lateral displacement date were approximated by Fourier series and the lateral displacement was decomposed into four types of component. The were isotropoic displacement, anisotropic displacement, parallel movement and the displacement by the shearing along the generated fracture. From this analysis, it was cleared that the isotropic component was dominant until the apparent stress drop was observed and after that , the displacement according to the shearing was dominant when the specimen was brittle. On the other hand, when the specimen was plastic, the isotropic component was dominant all through the test. Mo … More reover, it was cleared that the component of parallel movement was sppeared from the start of the test and the anisotropic component started to appear just before or after the peak strength. Second, the maximun lateral displacement was calculated for all the rock types. From this analysis, it was cleared that in the case of Akiyioshi marble, the displacement generated by the isotropic component was larger than that by the shearing along generated fracture. In the case of Shirahama sandstone, it was cleared that the magnitude of the maximum lateral displacement genreated by the isotropic component was almost the same to that by the shearing. Furthermore, in the case of Berea sandstone, it was cleared that the maximum displacement was caused by the shearing. Last, the progress of inner failure of Akiyoshi marble was detected by using X-ray CT scanner and the relation between the lateral displacement and the inner failure of the specimen. From this analysis, it was detected that the inner failure became large according to the progress of axial strain and the direction of apparent fracture was perpendicular to the diectiron of dominant inner failure. Less