A simplified analysis method for piled raft foundations subjected to ground movements induced by tunnelling     

Pastsakorn Kitiyodom  Tatsunori Matsumoto  Kanji Kawaguchi 《国际地质力学数值与分析法杂志》2005,29(15):1485-1507

A simplified method of numerical analysis has been developed to estimate the deformation and load distribution of piled raft foundations subjected to ground movements induced by tunnelling and incorporated into a computer program ‘PRAB’. In this method, a hybrid model is employed in which the flexible raft is modelled as thin plates, the piles as elastic beams, and the soil is treated as interactive springs. The interactions between structural members, pile–soil–pile, pile–soil–raft and raft–soil–raft interactions, are modelled based on Mindlin's solutions for both vertical and lateral forces. The validity of the proposed method is verified through comparisons with some published solutions for single piles and pile groups subjected to ground movements induced by tunnelling. Thereafter, the solutions from this approach for the analysis of a pile group and a piled raft subjected to ground movements induced by tunnelling are compared with those from three‐dimensional finite difference program. Good agreements between these solutions are demonstrated. The method is then used for a parametric study of single piles, pile groups and piled rafts subjected to ground movements induced by tunnelling. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Spatial variation in organic matter utilization by benthic communities from Yura River–Estuary to offshore of Tango Sea,Japan     

Emily S. Antonio  Akihide Kasai  Masahiro Ueno  Nam-il Won  Yuka Ishihi  Hisashi Yokoyama  Yoh Yamashita 《Estuarine, Coastal and Shelf Science》2010

We investigated the distribution of δ¹³C and δ¹⁵N of organic matter among benthic communities from the upper estuary of Yura River to offshore of Tango Sea, Japan, to determine spatial variation in utilization of organic matter by benthic communities. The δ¹³C values of benthic animals ranged from −27 to −15‰ in the upper estuary, −21 to −15‰ in the lower estuary, −20 to −16‰ in the shallow coast (5–10 m depths), −18 to −16‰ in the deep coast (30–60 m depths) and −19 to −15‰ in offshore (100–150 m depths) stations. Adapting the dual isotope values to mixing models, we estimated the relative contributions of potential food sources to the benthos diet. Phytoplankton and macroalgae that intruded the estuary in summer were utilized as alternative food aside from the terrestrial-origin organic matter assimilated by the estuarine benthic consumers. Resuspended benthic microalgae were important source of energy in the shallow coastal stations, while abundant supply of phytodetritus fueled the deep coastal and offshore benthic food webs. Spatial difference in the diet of benthic communities depends largely on the shifts in the primary carbon source. Thus, benthic communities are important link of autochthonous/allochthonous production and secondary production in the continuous river–estuary–marine system.  相似文献   

Production de²⁶Al dans Fe et Si par protons de 0.6 et 24 GeV     

S. Regnier  M. Lagarde  G.N. Simonoff  Y. Yokoyama 《Earth and Planetary Science Letters》1973,18(1):9-12

A total of 139 breccia and crystalline rock fragments in the size range 2–4 mm from four Apollo 15 soil samples have been examined. Two of the sample stations are on the mare surface (4 and 9A) and two are on the Apennine Front (2 and 6). Approximately 90% of the fragments from the Apennine Front are brown-glass “soil” breccias, but those from the mare surface are 60%–70% basalt. Several textural varieties of mare basalt have been recognized, but within experimental error there is no difference in their⁴⁰Ar-³⁹Ar ages. The major non-mare (Pre-Imbrian) crystalline rock types in the Apennine Front regolith are KREEP basalt, anorthositic rocks, recrystallized norite (including anorthositic norite) and recrystallized polymict breccias; however, such crystalline rocks are rare in the samples examined. Apparently, the near surface Imbrium ejecta below the regolith has not been thermally recrystallized, and probably there are no outcrops of crystalline rocks upslope from the sample stations.  相似文献   

Nikubuchi peridotite body in the sanbagawa metamorphic belt; thermal history of the ‘Al-pyroxene-rich suite’ peridotite body in high pressure metamorphic terrain     

Kazumi Yokoyama 《Contributions to Mineralogy and Petrology》1980,75(1):1-13

Oceanic tholeiite glass has been reacted with natural seawater at 25°–500° C, 1 kbar, with both low (5) and high (50) water/rock mass ratios. Initial experiments were conducted at constant temperatures between 100° C and 500° C (100° intervals) in order to characterize the mineralogy and chemical exchange trends for both water/rock ratios. However, the primary purpose of this investigation was to study the chemical and mineralogical changes that may take place as reacted seawater cools as it traverses a temperature gradient before exiting onto the seafloor, as may happen in some submarine hydrothermal systems. Consequently, a series of cooling or temperature gradient experiments were performed in which seawater that had reacted with basalt at 500° C was cooled to 25° C in a step-wise fashion; mineralogy and fluid chemistry were determined at 100 degree intervals during cooling.For all of the experiments, the elemental exchange trends were the same. With respect to the initial sea-water, Fe, Mn, Ca, Si and H⁺ increased while Na and Mg decreased. However, the extent of the exchange depended heavily on the temperature and water/rock ratio. During cooling, fluid compositions in the temperature gradient runs generally approached those of the constant temperature experiments. Even though fluid compositions were very similar at 500° C for both water/rock ratios, the high water/rock ratio systems were more efficient in leaching transition metals from the rock and maintained substantial concentrations in solution during cooling, even to temperatures as low as 25° C. The Fe/Mn ratio in the fluid, however, was quite different for the two water/rock ratios; consequently, the effective water/rock ratio appears to be one parameter that can control the Fe/Mn ratio in exiting hydrothermal fluids and may influence the Fe/Mn ratio in metal-rich sediments.Alteration minerals produced in these seawater/ basalt experiments are very similar to those found at submarine springs on the East Pacific Rise, 21° N. Iron sulfides, pyrite and pyrrhotite, precipitated during cooling for both water/rock ratios, demonstrating the ore-forming potential of submarine hydrothermal systems.  相似文献   

Paleomagnetic stratigraphy and biostratigraphy of the Plio-Pleistocene in the Kinki district, Japan     

Kazuaki Maenaka  Takuo Yokoyama  Shiro Ishida 《Quaternary Research》1977,7(3):341-362

The magnetostratigraphic subdivision of the Plio-Pleistocene series in the Kinki district around Osaka in southwest Japan, based on NRM measurements of volcanic ash beds, is correlated with biostratigraphic and paleoclimatic marker beds as well as past sea level oscillations. At least 10 high sea level stands occurred in the study area between about 1.5 and 0.27 million years ago, all associated with relative warming. A significant change in the composition of flora, from Metasequoia to Fagus dominated assemblages, was observed around the Jaramillo event.  相似文献   

Determination of210Pb in volcanic gases and210Pb,226Ra,238U in lavas by non-destructive gamma-ray spectrometry     

Y. Yokoyama  H. Van Nguyen  G. Lambert 《Bulletin of Volcanology》1982,45(3):265-266

  相似文献   

A gravity survey on Volcano Huzi,Japan by means of a Worden gravimeter     

Yokoyama  Izumi  Tajima  Hirokazu 《Pure and Applied Geophysics》1960,45(1):1-12

Summary Observations and reductions of the gravimeter survey on Volcano Huzi are fully described. The survey was accompanied by various inevitable difficulties but the accuracy of calculating the Bouguer anomalies is kept high enough to bear volcanological discussion. The results are rather suggestive to the theory of caldera-formation. Comparison with the gravity anomaly on the volcanic islands in the middle of the ocean is also made.  相似文献   

Crustal structures that produce eruptions of welded tuff and formation of calderas     

I. Yokoyama 《Bulletin of Volcanology》1966,29(1):51-60

Accumulation of a huge amount of welded tuff and subsequent formation of calderas are typical examples of volcanisms on a large scale. Crustal structures which are related to the phenomena may be a key for the study of volcanisms on the earth. In Japan there are some 10 calderas of low gravity anomaly type, large and small in diameter, and accordingly in volume of their ejecta, welded tuff. The low gravity anomalies are very characteristic inside the calderas and just concentric with their rims, and are due to mass deficiency caused by eruptions of a huge amount of ejecta. The author (1957), hitherto, has clarified the subterranean structures resulting from the caldera formations by a gravimetric method. In this paper, the author describes the crustal structures beneath Sikotu Caldera in Hokkaido, Japan, deduced from the gravimetric, geomagnetic, seismic and geologic surveys. And referring several examples of the subterranean structures of the other calderas in Japan, the author wishes to discuss the crustal structures that would produce the caldera formations.  相似文献   

SHRIMP and electron microprobe chronology of UHT metamorphism in the Napier Complex,East Antarctica: implications for zircon growth at >1,000 °C     

Tomokazu?HokadaEmail author  Keiji?Misawa  Kazumi?Yokoyama  Kazuyuki?Shiraishi  Akira?Yamaguchi 《Contributions to Mineralogy and Petrology》2004,147(1):1-20

Zircons in ultra-high-temperature (UHT) metamorphosed paragneisses from Mt. Riiser-Larsen in the Napier Complex, East Antarctica, were dated by using ion microprobe (SHRIMP) and electron microprobe (EMP). Both SHRIMP and EMP analyses yield consistent 2520–2460 Ma age populations for garnet–orthopyroxene-bearing paragneiss and leucosomes enclosed within. The peak UHT event was dated at 2480 Ma by SHRIMP analyses on metamorphic zircons from the garnet–orthopyroxene paragneiss and those on magmatic zircons from the leucosomes which are interpreted to be formed at syn-UHT. As obtained by SHRIMP, the UHT metamorphic event was terminated no later than 2460 Ma. Minor 2520-Ma SHRIMP age suggests either the onset of prograde metamorphism or another high-grade metamorphic event unrelated to the UHT. EMP analyses on metamorphic zircons from sapphirine–quartz and osumilite-bearing magnesian paragneisses give c. 2500–2450 Ma ages. Inherited igneous zircon cores of the magnesian paragneisses yield relatively scattered EMP ages ranging over c. 3000–2650 Ma, suggesting that igneous materials of these ages sourced the protoliths of the paragneisses and that they were deposited during the interval c. 2650–2520 Ma.  相似文献   

Earthquake-induced rapid long-traveling flow phenomenon: May 2003 Tsukidate landslide in Japan   总被引：3，自引：2，他引：1  

Hiroshi?Fukuoka  Gonghui?WangEmail author  Kyoji?Sassa  Fawu?Wang  Tatsunori?Matsumoto 《Landslides》2004,1(2):151-155

  相似文献