HR: 0830h
AN: T41D-0252    [PDF]
TI: Photogrammetrical fracture analysis of rock bodies
AU: * Fujii, Y
EM: fujii@fgi.or.jp
AF: Fukada Geological Institute, 2-13-12 Hon-Komagome Bunkyo-ku, Tokyo, 113-0021 Japan
AU: Hori, S
EM: horidpt@hf.rim.or.jp
AF: DPT Corporation, 1-1-4 Kyodo-building 2F Hattyoubori Chuo-ku, Tokyo, 104-0032 Japan
AB: We tried to introduce a new way to determine the 3-D distribution of a fracture system. The fractured rock bodies are stereo-photographed by a calibrated analog camera, and the photos were processed using a stereo-comparator to get raw data and the computer software to get the digital terrain model of the rock bodies and the 3-D distribution of the fracture systems. A target for this trial was chosen from the Cretaceous sandstone layers exposed in the Pacific Coast near Nakaminato, Ibaraki, which have been suffered different fracturing successively since its deposition. THe 3-D distribution of the fractures suggests the following facts. (1) Four sets of small scale faults are distinguished, making homogeneous domains; (2) Joints are not displaced by faults; (3) Joints are not continuous across the boundaries of the fault domains; (4) Each joint system developed within a fault-bounded is different in orientation,from that of neighboring. From these observations we can safely conclude that, in this particular case, faults are formed at first, making fault bounded blocks in the Cretaceous sandstone. Then joint systems were formed under subsequent stress condition, but according to the preexisting fault systems, resulted stress field were in different orientation according to the block. This suggests that the boundaries of the blocks gave new boundary condition when joints were formed. Joint systems were accordingly oriented to slightly different directions in neighboring blocks. This is only an example, but shows that this new method is useful enough for 3-D analysis of the fractures.
DE: 1224 Photogrammetry
DE: 8010 Fractures and faults
SC: Tectonophysics [T]
MN: 2003 Fall Meeting