Fluid flow through rock fractures is commonly described by the cubic law or parallel plate model. However, deviations from this model can be expected, because real fracture surfaces are rough and contact each other at discrete points. To examine this problem, realistic fracture surfaces were generated numerically by using a fractal model, and fracture flow analysis was carried out by FEM. It was found that deviations from the cubic law occurred when the surface contact area ratio increased to around 0.1. In addition, a hydromechanical analysis of rock slope with a single and inclined fracture was conducted and it was found that the distributions of water pressure in rock fractures were quite different from those obtained on the assumption of the cubic law.
Fluid flows through a rock fracture are commonly described by the cubic law or parallel plate model. However, deviations from this model are evident, because rock fracture surfaces are rough and contact each other at discrete points. The roughness of the fracture walls as well as the increasing contact area and flow path tortuosity at high normal stress must cause deviations from a parallel plate model in which the rate of flow through smooth walls is assumed to change with the cube of its opening. The scope and objective of the work is to demonstrate the importance of the non-cubic flow rules of rock fractures and its effects on the overall stability of rock slopes.
Japanese limestone mining consistently increased its production in accordance with the economic boom after the World War II in order to satisfy growing demand from cement, steel making, construction and chemical industries ? on the contrary, since the mid 1980s the collieties and metal mines in Japan have been gravely damaged and lost their economic competence owing to the soaring labor costs as well as a sharp decline in the market price of imported ores accelerated by the high appreciation of Japanese yen. The number of major mines still working at the end of January 2001 was only three in metal and another two in coal mining. The Japanese limestone mining is, however, quite vigorous and it is annually exploiting slightly less than 200 million tonnes. The limestone quarrying can be regarded as the most important mining industry in Japan; in fact, it is the second largest producer after USA among the former western countries.