Budget Amount *help |
¥4,300,000 (Direct Cost: ¥4,300,000)
Fiscal Year 1999: ¥4,300,000 (Direct Cost: ¥4,300,000)
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Research Abstract |
The mono-fractal dimension and geometric features of outcropping fractures in welded tuff and tuffaceous mudstone, and artificial 2D network models have been investigated. The fractal dimension of observed fracture sets were determined using the box-counting method, and several geometric characteristics including length distribution, orientation, connectivity, number of fractures, and total length of fractures were quantified in order to construct a two-dimensional fracture network model. The space filling fracturing of a welded tuff was represented by a single fractal dimension from 1.6 mm through 10 m square scales, however, an universal fractal property could not be observed in the case of tuffaceous mudstone in spite of fractal behavior at each scale. These differences of fractal features between the welded tuff and the tuffaceous mudstone are considered to be related to the mechanism of fracture generation and different fracture mechanical characteristics. Computer-generated two-di
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mensional fracture network patterns of the welded tuff utilizing the observed fractal dimension and geometric relationships have been found capable of simulating the natural fracture patterns. This artificial model, which is founded on the uniform fractal property of a given fracture set from microscopic to 10m scales in the welded tuff, is capable of being expanded to larger scales on the basis of self-similarity. In addition, monofractality of the fracture network in the Kurihashi granodiorite in the Kamaishi mMine was evaluated using the box-counting method. The fracture maps for fractal analysis were obtained by tracing fractures including open cracks, hydrothermal alteration veins and quartz vein at the scale mostly 2.0x4.0mィイD12ィエD1 on the wall rock of E. L. 250mL drift. The distribution of alteration veins shows monofractality with similar dimension (D from 1.04 to 1.11), which means that the distribution of alteration veins ranging from 1.5x1.5mィイD12ィエD1 to 2.5x360mィイD12ィエD1 could be characterized by an unique monofractal dimension. Less
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