Delayed plastic model for time‐dependent behaviour of materials     

Tsutomu Namikawa 《国际地质力学数值与分析法杂志》2001,25(6):605-627

A delayed plastic model, based on the theory of plasticity, is proposed to represent the time‐dependent behaviour of materials. It is assumed in this model that the stress can lie outside the yield surface and the conjugate stress called static stress is defined on the yield surface. The stress–strain relation is calculated based on the plastic theory embedding the static stress. Thus, the stress–strain relation of the model practically corresponds to that of the inviscid elastoplastic model under fairly low rate deformation. The delayed plastic model is coupled with the Cam‐clay model for normally consolidated clays. The performance of the model is then examined by comparing the model predictions with reported time‐dependent behaviour of clays under undrained triaxial conditions. It is shown that the model is capable of predicting the effect of strain rate during undrained shear and the undrained creep behaviour including creep rupture. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Temporal variations of the CO₂ concentration and its carbon and oxygen isotopic ratios in a temperate forest in the central part of the main island of Japan     

TAKAKIYO NAKAZAWA  SHOHEI MURAYAMA  MITSUKO TOI  MISA ISHIZAWA  KAORI OTONASHI  SHUJI AOKI  SUSUMU YAMAMOTO 《Tellus. Series B, Chemical and physical meteorology》1997,49(4):364-381

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The concentration of atmospheric carbon dioxide at the Japanese Antarctic Station, Syowa     

T. NAKAZAWA  S. AOKI  S. MURAYAMA  M. FUKABORI  T. YAMANOUCHI  H. MURAYAMA  M. SHIOBARA  G. HASHIDA  S. KAWAGUCHI  M. TANAKA 《Tellus. Series B, Chemical and physical meteorology》1991,43(2):126-135

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Flapping motions of the tail plasma sheet induced by the interplanetary magnetic field variations     

Toichi Tsutomu  Miyazaki Teruki 《Planetary and Space Science》1976,24(2):147-159

Flapping motions of the magnetotail with an amplitude of several earth radii are studied by analysing the observations made in the near (x = ?25 ~ ?30 R_E and the distant (x? ?60 R_E) tail regions. It is found that the flapping motions result from fluctuations in the interplanetary magnetic field, especially Alfvénic fluctuations, when the magnitude of the interplanetary magnetic field is larger than ~10 γ and they propagate behind the Earth with the solar wind flow. Flappings tend to be observed in early phases of the magnetospheric substorm, and they have two fundamental modes with periods of ~200 and ~500 sec. In some limited cases a good correspondence with the long period micropulsations (Pc5) in the polar cap region is observed. These observational results are explained by the model in which the Alfvénic fluctuations in the solar wind penetrate into the magnetosphere along the connected interplanetary-magnetospheric field lines. The characteristics of the flapping reveal that the geomagnetic tail is a good resonator for the hydromagnetic disturbances in the solar wind.  相似文献   

Application of multi-isotope ratios to study the source and quality of urban groundwater in Metro Manila,Philippines   总被引：1，自引：0，他引：1  

Takahiro Hosono  Fernando Siringan  Tsutomu Yamanaka  Yu Umezawa  Shin-ichi Onodera  Takanori Nakano  Makoto Taniguchi 《Applied Geochemistry》2010

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Cluster formation and the Sunyaev–Zel'dovich power spectrum in modified gravity: the case of a phenomenologically extended DGP model     

Tsutomu Kobayashi  Hiroyuki Tashiro 《Monthly notices of the Royal Astronomical Society》2009,398(1):477-484

We investigate the effect of modified gravity on cluster abundance and the Sunyaev–Zel'dovich (SZ) angular power spectrum. Our modified gravity is based on a phenomenological extension of the Dvali–Gabadadze–Porrati model which includes two free parameters characterizing deviation from Λ cold dark matter cosmology. Assuming that Birkhoff's theorem gives a reasonable approximation, we study the spherical collapse model of structure formation and show that while the growth function changes to some extent, modified gravity gives rise to no significant change in the linear density contrast at collapse time. The growth function is enhanced in the so called normal branch, while in the 'self-accelerating' branch it is suppressed. The SZ angular power spectrum is computed in the normal branch, which allows us to put observational constraints on the parameters of the modified gravity model using small scale cosmic microwave background observation data.  相似文献   

Carboniferous foraminifers from the lower part of Paleo-Tethyan seamount-type carbonates in the Changning-Menglian Belt, western Yunnan, Southwest China     

Tin Tin LATT  Tsutomu NAKAZAWA  WANG Xiang-dong  Katsumi UENO 《地球学报》2009,30(Z1):35-36

The Changning-Menglian Belt in West Yunnan, Southwest China is well-known as a closed remnant of the Paleo-Tethys Ocean in East Asia (Wu et al., 1995; Liu et al., 1996). It is delineated to the east with the Lincang Massif by the Changning-Shuangjiang Fault and to the west with the Baoshan Block by the Kejie-Nandinghe Fault, and is generally subdivided into three zones: east, central, and west zones. In the central zone, various kinds of oceanic rocks such as harzburgite, cumulate websterite, gabbro, both mid-oceanic ridge basalt and oceanic island basalt, Devonian-Triassic radiolarian chert, and Carbonifer-ous-Permian massive and huge carbonates with basaltic effusives as their pedestal are exposed (Liu et al., 1991, 1996; Wu et al., 1995; Ueno et al., 2003). These Central zone rocks are now interpreted to have been emplaced as nappes structurally overlying the East and West zones, which are considered as consisting mainly of passive margin sediments of the Baoshan Block (Wu, 1991; Ueno et al., 2003).  相似文献   

Jointing of two tunnel shields using artificial underground freezing     

Tsutomu Takashi  Shiro Kiriyama  Tetsuji Kato 《Engineering Geology》1979,13(1-4):519-529

Freezing was used in the jointing section of two shields (diameter 3.14 m) which ran across at right angles and at 25-m depth under the crossing of main roads for the construction of a 2.4-m diameter sewer tunnel. The object of freezing was to create a frozen barrier to prevent the inflow of water and fine sand into the area to be excavated.

Thirty-five freeze pipes (length about 7 m) were placed from one shield conically in the direction of the flank of another shield with freeze pipes attached to its inside wall. The cooling unit was placed on unoccupied land at about 60 m distant from the jointing section and the freeze pipes were connected with the cooling unit by supply and return pipelines.

The cooling unit had a cooling capacity of 79,000 kcal/h at an evaporation temperature of −27°C and a condensation temperature of +40°C. Freezing was continued for 180 days and the CaCl₂ brine temperature was −25 to −30°C. These works were accomplished without the sinking of shaft and the use of injection, in complete safety with no traffic restriction on the road surface.  相似文献   

Mineralogical and Geochemical Constraints on Arsenic Mobility in a Philippine Geothermal Field     

Chelo PASCUA Tsutomu SATO Glenn GOLLA 《《地质学报》英文版》2006,80(2):230-235

Arsenic is usually associated with sulphide minerals formed in the geothermal environment. However, sulphide minerals are prone to dissolution after contact with meteoric water under surface oxidizing conditions. Secondary precipitates that form from the dissolution of the primary sulfides exert a greater influence on arsenic mobility in the geothermal environment. Fe-hydroxides have very good affinity with dissolved arsenate and are stable under most surface oxidizing conditions. Both amorphous silica directly precipitated from geothermal fluids and possibly a kaolinite alteration can host a small significant amount of arsenic. These silicates are also more stable under a wide range of pH and redox conditions.  相似文献   

在可控制的相对湿度下矿物表面上多环芳烃的降解     

Shuji TAMAMURA  Tsutomu SATO  Yukie OTA  Kazuichi HAYAKAWA 《地质学报》2006,80(4):616

多环芳香烃由于诱发突变和致癌的性质威胁着人类的健康,近年来,其降解问题得到了广泛的关注。笔者研究了在没有光照的条件下,改变相对湿度(5%至30%之间),苯并芘(一种典型的多环芳烃物质)在石英,矾土,蒙脱石,高岭石,腐殖酸和吸附了腐殖酸的石英上的稳定性,继而可以检测出矿物表面催化多环芳烃降解的效果。苯并芘的稳定性主要是由吸附剂的物化性质决定的。石英表现出很好的催化效果,即便其表面被腐殖酸所包覆。在整个实验过程中(3天)吸附在蒙脱石和腐殖酸表面的苯并芘依然很稳定。实验装置中的湿度影响在某些特定的矿物中的苯并芘的稳定性。特…  相似文献