A Few Remarks on Examination of Cavities or Microcracks produced in Rocks using a Fluorescent Substance

• Published in: Journal of the Japan Society of Engineering Geology Vol. 33; no. 1; pp. 17 - 22
• Main Authors: KUSUDA, Hiromu, SAITO, Toshiaki, NISHIYAMA, Takashi
• Format: Journal Article
• Language: English
• Published: Japan Society of Engineering Geology 1992
• Subjects: cavity; fluorescent method; image analysis; microcrack; weathering
• ISSN: 0286-7737; 1884-0973
• DOI: 10.5110/jjseg.33.17

Applications of data on cracks andcavities in rocks are numerous and varied, in terms of both academic research and practical use. Important current research topics include the precise workings of microcracking processes and the effect of a variety of environmental condition on weathering. The propagation paths in granite, tuff and sandstone and the changes of cracks and cavities produced in specimens of tuff by weathering result, on a microscopic scale, were examined. Microcracks and cavities in specimens of granite, sandstone and weathered tuff were filled with methylmetaacrylate mixed with fluorescent paint, and then microscopically visualized under ultraviolet ray. The image analysis was performed to clarify the state of microcracks and cavities within the rock specimens by coating the specimens with fluorescent resin. Time control on weathering processespresentsclear examples of the stages in the evolution of microcracks, pathways of ground-water, and fillings of microcracks with secondary products. It is observed that the repeated occurrence of microcracks and diffusion enlargement is due to a periodic system dominated by the chemical or mechanical weathering rates. Image analysis using differences in brightness between microcracks or cavities filled with fluorescent resin and other parts of the specimen, was done, and the results showed good agreement with the porosity and the P-wave velocitydetermined by the usual methods. This new method may be useful for assessing the grade of microcracking or weathering.