岩盤中の割れ目系にみられるフラクタル

抄録

For modeling groundwater flow and mechanical responses of fractured rock mass, to grasp the characteristics of fractures is essentially needed. Recently, the concept of fractal has been applied by some researchers to describe the fracture system. In this study, the authors report a statistical approach made to check the adaptability of the concept of fractal to the fracture system.
The lengths of fracture-traces, apperently seen on the surface of rock mass, were measured by sketching and utilizing data of linearment analysis, while the widths of fracture-traces recognized on geological logs and maps were guaged. The measured data of fracture-traces were statistically processed to determine the distribution functions in large and small scales, then, cumulative-frequency curves were examined.
Although log-normal distributions were commonly observed for any measured scales, detailed discussion on scale effect in measurement led us that the measurement error and loss of information became larger as the size of fracture-trace became smaller or larger relative to average value of the resolution of human eyes and the objective scales. Removing such effects, the distribution of measured data within a scale was deviated from log-normal, but was correlated approximately by power distribution, indicating that the fracturetraces possibly distribute obeying so-called “Fractal distribution”. The authors prospect that this fact might be useful for estimating reasonably the distribution and the characteristic factors of fractures of any scale from the measurements at available scales.