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Kurosaki, Yukio*; Yamachi, Hiroshi*; Matsui, Hiroya
JAEA-Research 2008-066, 168 Pages, 2008/09
JAEA-Research-2008-066-1.pdf:21.59MBJAEA-Research-2008-066-2.pdf:45.71MBJAEA-Research-2008-066-3.pdf:18.64MBJAEA-Research-2008-066-4.pdf:3.35MB
Mizunami underground research laboratory planned to excavate to 1000 m depth and now under construction. One of the most serious problems in a greatly deeper shaft is "TAKANUKE" collapse caused by slip movement of large discontinuities. In this report, we have conducted numerical studies using finite difference method in order to throw an objective light on a mechanism of TAKANUKE collapse. These studies show two different stress states in upper and lower side of large discontinuities. In order to evaluate a possibility of TAKANUKE collapse during MIZUNAMI main shaft sinking, we have conducted a particle body analysis as well. A fault with a high strike up to 79 degree, discovered in survey boring at MIZUNAMI site, has a low potential of TAKANUKE collapse during shaft sinking.
Kurosaki, Yukio*; Yamachi, Hiroshi*; Katsunuma, Yoshio*; Nakata, Masao*; Kuwahara, Hideki*; Yamada, Fumitaka*; Matsushita, Kiyoshi*; Sato, Toshinori*
JAEA-Research 2008-048, 274 Pages, 2008/03
JAEA-Research-2008-048.pdf:10.93MB
A junction space between a super deep shaft and horizontal drifts forms a 3-dimensional geo-structure, which would take a complicated mechanical behavior during a junction excavation. However, a quantitative design method for a deep junction has not yet established. In order to examine a collapse mechanism of super deep shaft junction, we have conducted literature surveys and interview studies concerned with a collapses. Considering the results of investigations with reviews of intellectuals, the collapse mechanism depends on both a construction procedure of shaft junction and a geological condition. On the other hand, where a deep junction intersects faults and/or fractures with a large angle, a collapse called taka-nuke may occur and a numerical studies that can simulate a practical rock mass behavior around a shaft junction should be carry out. We demonstrate finite difference method is most adequate for these simulations with intellectual review.