岩石亀裂の粗さの定量化と強度・変形特性に関する研究
亀裂の表面形状はその強度・変形特性に大きく影響する。従来は粗さの程度を目視観察によって判定してきたため、客観性に乏しかった。そこで亀裂の粗さをフラクタル次元で客観的かつ定量的に評価する方法の提案を行い、現状で最も利用されている粗さ指標の一つであるJRC値との相関を求めた。3種類の岩石ブロックを割裂して作成した人工亀裂および3ヶ所で採取した天然亀裂の粗さの評価を行った。次に室内試験で亀裂のせん断強度、せん断剛性・垂直剛性を把握し、人工亀裂と天然亀裂の比較およびBBモデルから推定される物性との比較も行った。
A Study on the Method of Quantitating Joint Roughness, Shear Strength and Deformation Behavior
Joint surface roughness is a very important factor in shear strength and deformation behavior. The joint roughness coefficient (JRC) proposed by Barton is one of the most useful degree of joint roughness. However the JRC can not be assessed objectively because it is usually judged by visual observation. In this paper, the authors propose an objective method for the quantitation of joint roughness by using fractal dimensions. The relation of fractal dimensions and JRC is mentioned. The fractal dimensions and JRC of three types of artificial joint and three types of natural joints are analyzed. The shear strength, shear and normal stiffness of joints are investigated by laboratory tests, the difference between artificial and natural joints and the comparison the test results with the Barton-Bandis model (BB model) are discussed.