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101.
Jonny Rutqvist Ann Bäckström Masakazu Chijimatsu Xia-Ting Feng Peng-Zhi Pan John Hudson Lanru Jing Akira Kobayashi Tomofumi Koyama Hee-Suk Lee Xiao-Hua Huang Mikael Rinne Baotang Shen 《Environmental Geology》2009,57(6):1313-1324
This simulation study shows how widely different model approaches can be adapted to model the evolution of the excavation
disturbed zone (EDZ) around a heated nuclear waste emplacement drift in fractured rock. The study includes modeling of coupled
thermal-hydrological-mechanical (THM) processes, with simplified consideration of chemical coupling in terms of time-dependent
strength degradation or subcritical crack growth. The different model approaches applied in this study include boundary element,
finite element, finite difference, particle mechanics, and elasto-plastic cellular automata methods. The simulation results
indicate that thermally induced differential stresses near the top of the emplacement drift may cause progressive failure
and permeability changes during the first 100 years (i.e., after emplacement and drift closure). Moreover, the results indicate
that time-dependent mechanical changes may play only a small role during the first 100 years of increasing temperature and
thermal stress, whereas such time-dependency is insignificant after peak temperature, because of decreasing thermal stress. 相似文献
102.
103.
Kenta Kobayashi Satoshi Hirano Takashi Arai Ryuji Ikeda Kentaro Omura Hiroyuki Sano Takashi Sawaguchi Hidemi Tanaka Tomoaki Tomita Naoto Tomida Tatsuo Matsuda Akiko Yamazaki 《Island Arc》2001,10(3-4):411-421
Abstract Characteristics of deformation and alteration of the 1140 m deep fracture zone of the Nojima Fault are described based on mesoscopic (to the naked eye) and microscopic (by both optical and scanning electron microscopes) observations of the Hirabayashi National Research Institute for Earth Science and Disaster Prevention (NIED) drill core. Three types of fault rocks; that is, fault breccia, fault gouge and cataclasite, appear in the central part of the fault zone and two types of weakly deformed and/or altered rocks; that is, weakly deformed and altered granodiorite and altered granodiorite, are located in the outside of the central part of the fault zone (damaged zone). Cataclasite appears occasionally in the damaged zone. Six distinct, thin foliated fault gouge zones, which dip to the south-east, appear clearly in the very central part of the fracture zone. Slickenlines plunging to the north-east are observed on the surface of the newest gouge. Based on the observations of XZ thin sections, these slickenlines and the newest gouge have the same kinematics as the 1995 Hyogo-ken Nanbu earthquake (Kobe earthquake), which was dextral-reverse slip. Scanning electron microscopy observations of the freeze-dried fault gouge show that a large amount of void space is maintained locally, which might play an important role as a path for fluid migration and the existence of either heterogeneity of pore fluid pressure or strain localization. 相似文献
104.
105.
The thermal diffusivity of synthetic polycrystalline stishovite was determined by the Ångstrom method in the temperature range 300–550 K at 1 atm. The calculated thermal conductivity of stishovite at 300 K is 0.086 W cm?1 K?1 which is comparable to that for TiO2-rutile but much lower than for GeO2 and SnO2. The observed thermal conductivities of rutile-structure oxides increase systematically with increasing density, in contrast with the expected behavior for isostructural compounds. 相似文献
106.
Equivalent linear method considering frequency dependent characteristics of stiffness and damping 总被引:4,自引:0,他引:4
Nozomu Yoshida Satoshi Kobayashi Iwao Suetomi Kinya Miura 《Soil Dynamics and Earthquake Engineering》2002,22(3)
Equivalent linear dynamic response analysis of ground is based on complex moduli and Fourier series expansion; therefore, it is not an equivalent method but an approximate method. Two deficiencies in the conventional equivalent linear method represented by SHAKE are described first. The maximum shear strength is overestimated, resulting in overestimation of the peak acceleration under a strong ground motion, and the amplification is underestimated at high frequency. The latter sometimes results in underestimation of the peak acceleration under weak ground shaking, and gives an incident wave with unrealistic large accelerations or a divergence of analysis in deconvolution analysis under strong ground motion. Both deficiencies are shown to come from the same cause, i.e. computing the effective strain as a constant fraction of the maximum strain. Since this is a key concept of the equivalent linear analysis, one cannot overcome both deficiencies at the same time in the conventional method. An apparent frequency dependence in stiffness and damping is shown to appear in the dynamic response, although soil itself does not show frequency dependent characteristics. Following this observation, the effective strain is expressed in terms of frequency from the similarity concept of the strain–frequency relationship between time domain and frequency domain. This enables the reduction of both deficiencies at the same time, resulting in a marked improvement in the equivalent linear analysis. The accuracy of the proposed method is examined by the simulations of three vertical array records during large earthquakes. The proposed method always gives much better prediction than conventional equivalent linear methods for both convolution and deconvolution analyses, and it is confirmed to be applicable at more than 1% shear strain. 相似文献
107.
Numerical studies on the influence of the variations of the Kuroshio Path on the transport of fish eggs and larvae 总被引:2,自引:0,他引:2
Main spawning and nursery grounds of the Pacific Sardine are formed in the coastal boundary regions of the Kuroshio S of Kyushu
and S of Honshu, respectively. Numerical experiments on the transport and dispersion of particles in and neighbouring areas
of the Kuroshio were done to investigate the transport process of the fish eggs and larvae from the spawning ground to the
downstream nursery ground. Surface currents measured with GEK in the past were averaged for both paths with and without large
meanders of the Kuroshio in the S of Honshu and used as the data basis. Particles were released in the Kuroshio SE of Kyushu.
The results show that the transport rate of them into the S coastal waters of Honshu during large meandered path is larger
than the rate during the straight path period. However, recruitment rates of the Pacific Sardine in the S coastal waters of
Honshu decreases during the large meander periods of the Kuroshio path. This inverse correlation is considered to be caused
by the poorer food environment strongly influenced by the intrusion of the Kuroshio water. 相似文献
108.
Audrey Kobayashi 《The Professional geographer》1994,46(1):73-80
My experiences combining research and activism within the Japanese-Canadian community reflect a growing concern among feminist and anti-racist scholars with the politics of work among people marginalized by racism and sexism. This concern arises within a context where “other voices” are being heard, but the legitimacy of one individual or group to represent another is being challenged. Such challenges require that essentialism and naturalism be addressed politically and theoretically, a difficult irony given the need to utilize essentialist categories to address the oppressive conditions under which they emerged. To do so, a critical theory of political construction is required. 相似文献
109.
Jean-Paul Cadet Kazuo Kobayashi Jean Aubouin Jacques Boulgue Christine Deplus Jacques Dubois Roland von Huene Laurent Jolivet Toshihiko Kanazawa Junzo Kasahara Kinichiro Koizumi Serge Lallemand Yasuo Nakamura Guy Pautot Kiyoshi Suyehiro Shin Tani Hidekazu Tokuyama Toshitsugu Yamazaki 《Earth and Planetary Science Letters》1987,83(1-4)
This paper presents the results of a detailed survey combining Seabeam mapping, gravity and geomagnetic measurements as well as single-channel seismic reflection observations in the Japan Trench and the juncture with the Kuril Trench during the French-Japanese Kaiko project (northern sector of the Leg 3) on the R/V “Jean Charcot”. The main data acquired during the cruise, such as the Seabeam maps, magnetic anomalies pattern, and preliminary interpretations are discussed. These new data cover an area of 18,000 km2 and provide for the first time a detailed three-dimensional image of the Japan Trench. Combined with the previous results, the data indicate new structural interpretations. A comparative study of Seabeam morphology, single-channel and reprocessed multichannel records lead to the conclusion that along the northern Japan Trench there is little evidence of accretion but, instead, a tectonic erosion of the overriding plate. The tectonic pattern on the oceanic side of the trench is controlled by the creation of new normal faults parallel to the Japan Trench axis, which is a direct consequence of the downward flexure of the Pacific plate. In addition to these new faults, ancient normal faults trending parallel to the N65° oceanic magnetic anomalies and oblique to the Japan trench axis are reactivated, so that two directions of normal faulting are observed seaward of the Japan Trench. Only one direction of faulting is observed seaward of the Kuril Trench because of the parallelism between the trench axis and the magnetic anomalies. The convergent front of the Kuril Trench is offset left-laterally by 20 km relative to those of the Japan Trench. This transform fault and the lower slope of the southernmost Kuril Trench are represented by very steep scarps more than 2 km high. Slightly south of the juncture, the Erimo Seamount riding on the Pacific plate, is now entering the subduction zone. It has been preceded by at least another seamount as revealed by magnetic anomalies across the landward slope of the trench. Deeper future studies will be necessary to discriminate between the two following hypothesis about the origin of the curvature between both trenches: Is it due to the collision of an already subducted chain of seamounts? or does it correspond to one of the failure lines of the America/Eurasia plate boundary? 相似文献
110.
X. Ding S.-Y. Jiang K.-D. Zhao E. Nakamura K. Kobayashi P. Ni L-X. Gu Y.-H. Jiang 《Mineralogy and Petrology》2006,86(1-2):29-44
Summary Zircons from a granodiorite porphyry at the Wushan copper deposit in the Lower Changjiang Metallogenic Belt, east central
China, were dated using a Cameca IMS 1270 secondary ion mass spectrometer (SIMS); their chemical compositions and Hf isotopes
were analyzed using a JEOL JX A8800 electron microprobe (EMPA) and a Neptune LA-MC-ICP-MS, respectively. The U–Pb dating of
zircon reveals two age groups for the granodiorite porphyry; i.e. 144.6 ± 3.9 Ma and 121.0 ± 2.5 Ma. Zircons of the two age
populations display distinct chemical compositional characteristics with respect to UO2/HfO2 ratios, and show a negative correlation of (UO2 + Y2O3 + ThO2) and HfO2. The older age group of ∼145 Ma, defined by the majority of the zircons, is interpreted as the magmatic emplacement age,
whereas the younger age group of ∼121 Ma is interpreted as rejuvenation due to subsequent thermal or hydrothermal events.
Other interpretations such as presence of two distinct magmatic crystallization stages or inheritance of the older zircons
are also discussed in the paper. The ∼145 Ma magmatism at Wushan is consistent with the ages of most of the granitods in the
Lower Changjiang Metallogenic Belt. The Hf isotope composition of zircons (ɛHf = −2.1 and −7.0; TDMHf ages = 0.87 and 1.05 Ga), together with other available geochemical and Sr–Nd isotope data suggest that the granodioritic
magma was derived from mixing of juvenile mantle with older crustal material. Due to the close spatial and temporal relationship
of the granodiorite porphyry and the skarn mineralization at Wushan, the magamatic hydrothermal mineralization likely took
place between 145 Ma and 121 Ma, likely around 121 Ma. 相似文献