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   

Water saturated phase relations of some andesites with application to the estimation of the initial temperature and water pressure at the time of eruption     

Toshimori Sekine  Takashi Katsura  Shigeo Aramaki 《Geochimica et cosmochimica acta》1979,43(8):1367-1376

Near-liquidus phase relations in one-atmosphere dry and water-saturated high pressure conditions were experimentally determined on products of three historic andesitic eruptions. Run conditions ranged from 900 to 1100°C, at pressures up to 1500 bars with fO₂ controlled close to the nickel-nickel oxide (NNO) buffer. In order to represent the compositions of the true liquid parts of the erupting magmas, groundmass portions were mechanically separated from the porphyritic andesites. Such groundmass materials should lie exactly on the liquidus field boundary between the phases precipitating from the magma just prior to eruption under the prevailing P-T condition.All the samples showed a crossing of the plagioclase and orthopyroxene liquidi in the pressure-temperature range from 1 to 800 bar and 950–1090°C. The crossing condition approximates the magmatic condition immediately prior to eruption. In the case of the 1970 eruption of Akita-komagatake, the crossing point is at 150 bar and 1090°C, matching closely the observed explosive gas pressure and the temperature. In both cases of the 1783 eruption of Asama and the 1914–1915 eruption of Sakurajima volcanoes, the crossing point shift from higher water pressure and lower temperature for the earlier erupting magmas to lower pressure and higher temperature for the later magmas. This regularity may be explained by a vertical gradient of the temperature and water content within the magma column prior to eruption.  相似文献   

Impact of road‐generated storm runoff on a small catchment response     

Daniel W. Woldie  Roy C. Sidle  Takashi Gomi 《水文研究》2009,23(25):3631-3638

The impact of road‐generated runoff on the hydrological response of a zero‐order basin was monitored for a sequence of 24 storm events. The study was conducted in a zero‐order basin (C1; 0·5ha) with an unpaved mountain road; an adjacent unroaded zero‐order basin (C2; 0·2 ha) with similar topography and lithology was used to evaluate the hydrological behaviour of the affected zero‐order basin prior to construction of the road. The impact of the road at the zero‐order basin scale was highly dependent on the antecedent soil‐moisture conditions, total storm precipitation, and to some extent rainfall intensity. At the beginning of the monitoring period, during dry antecedent conditions, road runoff contributed 50% of the total runoff and 70% of the peak flow from the affected catchment (C1). The response from the unroaded catchment was almost insignificant during dry antecedent conditions. As soil moisture increased, the road exerted less influence on the total runoff from the roaded catchment. For very wet conditions, the influence of road‐generated runoff on total outflow from the roaded catchment diminished to only 5·4%. Both catchments, roaded and unroaded, produced equivalent amount of outflow during very wet antecedent conditions on a unit area basis. The lag time between the rainfall and runoff peaks observed in the unroaded catchment during the monitoring period ranged from 0 to 4 h depending on the amount of precipitation and antecedent conditions, owing mainly to much slower subsurface flow pathways in the unroaded zero‐order basin. In contrast, the lag time in the roaded zero‐order basin was virtually nil during all storms. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

In-situ survey of nanomolar manganese in seawater using an autonomous underwater vehicle around a volcanic crater at Teishi Knoll,Sagami Bay,Japan     

Takashi Doi  Michiaki Takano  Kei Okamura  Tamaki Ura  Toshitaka Gamo 《Journal of Oceanography》2008,64(3):471-477

We present the results of a chemical survey at a submarine volcano, Teishi Knoll, obtained using a submersible in-situ Mn analyzer (GAMOS) mounted on an autonomous underwater vehicle (AUV) platform. During this survey, high-resolution data of dissolved Mn were obtained in three dimensions in nearly real time. The AUV enabled continuous detailed observations along a preprogrammed pathway, which could not have been performed with conventional CTD hydrocasts. During this observation, anomalously high dissolved Mn concentrations were obtained within the crater, corresponding to high water temperatures. The anomalies might be a hydrothermal signature due to volcanic activity from the crater.  相似文献   

Corrigendum to “Climatological mean and decadal change in surface ocean pCO₂, and net sea–air CO₂ flux over the global oceans” [Deep Sea Res. II 56 (2009) 554–577]     

Taro Takahashi  Stewart C. Sutherland  Rik Wanninkhof  Colm Sweeney  Richard A. Feely  David W. Chipman  Burke Hales  Gernot Friederich  Francisco Chavez  Christopher Sabine  Andrew Watson  Dorothee C.E. Bakker  Ute Schuster  Nicolas Metzl  Hisayuki Yoshikawa-Inoue  Masao Ishii  Takashi Midorikawa  Yukihiro Nojiri  Arne Krtzinger  Tobias Steinhoff  Mario Hoppema  Jon Olafsson  Thorarinn S. Arnarson  Bronte Tilbrook  Truls Johannessen  Are Olsen  Richard Bellerby  C.S. Wong  Bruno Delille  N.R. Bates  Hein J.W. de Baar 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(11):2075-2076

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Editorial Appreciation     

John Leibacher  Takashi Sakurai  Lidia van Driel-Gesztelyi 《Solar physics》2016,291(2):337-338

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Differences in abundance and distribution of Alexandrium cysts in Sendai Bay,northern Japan,before and after the tsunami caused by the Great East Japan Earthquake     

Takashi Kamiyama  Hiroyuki Yamauchi  Satoshi Nagai  Mineo Yamaguchi 《Journal of Oceanography》2014,70(2):185-195

The tsunami caused by the Great East Japan Earthquake on 11 March 2011 greatly influenced the coastal benthic environment on the northern Pacific coast of Japan. We used the direct count method to investigate changes in the abundance and distribution of Alexandrium (Alexandrium tamarense and Alexandrium catenella) cysts before and after the tsunami in Sendai Bay. Densities of Alexandrium cysts in sediments collected in summer 2011 ranged from 0 to 8,190 cysts cm^?3. In the western part of the bay, the density increased greatly after the tsunami, the highest density being approximately 10 times the density recorded in 2005. Molecular identification of single cysts with multiplex polymerase chain reaction (PCR) showed that Alexandrium tamarense dominated the cyst population in the southwestern part of the bay in 2011. Furthermore, accumulation of cysts on the surface sediment after disturbance of the sediment was confirmed by a laboratory experiment. The main factor causing the drastic changes in abundance and distribution of Alexandrium cysts after the earthquake was considered to be vertical and horizontal redistribution of the cysts in sediments after the tsunami.  相似文献   

Primary melt from Sannome-gata volcano,NE Japan arc: constraints on generation conditions of rear-arc magmas     

Takeshi?KuritaniEmail author  Takeyoshi?Yoshida  Jun-Ichi?Kimura  Toshiro?Takahashi  Yuka?Hirahara  Takashi?Miyazaki  Ryoko?Senda  Qing?Chang  Yoshinori?Ito 《Contributions to Mineralogy and Petrology》2014,167(2):969

The conditions under which rear-arc magmas are generated were estimated using primary basalts from the Sannome-gata volcano, located in the rear of the NE Japan arc. Scoriae from the volcano occur with abundant crustal and mantle xenoliths, suggesting that the magma ascended rapidly from the upper mantle. The scoriae show significant variations in their whole-rock compositions (7.9–11.1 wt% MgO). High-MgO scoriae (MgO > ~9.5 wt%) have mostly homogeneous ⁸⁷Sr/⁸⁶Sr ratios (0.70318–0.70320), whereas low-MgO scoriae (MgO < ~9 wt%) have higher ⁸⁷Sr/⁸⁶Sr ratios (>0.70327); ratios tend to increase with decreasing MgO content. The high-MgO scoriae are aphyric, containing ~5 vol% olivine microphenocrysts with Mg# [100 × Mg/(Mg + Fe²⁺)] of up to 90. In contrast, the low-MgO scoriae have crustal xenocrysts of plagioclase, alkali feldspar, and quartz, and the mineralogic modes correlate negatively with whole-rock MgO content. On the basis of these observations, it is inferred that the high-MgO scoriae represent primary or near-primary melts, while the low-MgO scoriae underwent considerable interaction with the crust. Using thermodynamic analysis of the observed petrological features of the high-MgO scoriae, the eruption temperature of the magmas was constrained to 1,160–1,220 °C. Given that the source mantle was depleted MORB-source mantle, the primary magma was plausibly generated by ~7 % melting of a garnet-bearing spinel peridotite; taking this into consideration, and considering the constraints of multi-component thermodynamics, we estimated that the primary Sannome-gata magma was generated in the source mantle with 0.5–0.6 wt% H₂O at 1,220–1,230 °C and at ~1.8 GPa, and that the H₂O content of the primary magma was 6–7 wt%. The rear-arc Sannome-gata magma was generated by a lower degree of melting of the mantle at greater depths and lower temperatures than the frontal-arc magma from the Iwate volcano, which was also estimated to be generated by ~15 % melting of the source mantle with 0.6–0.7 wt% H₂O at ~1,250 °C and at ~1.3 GPa.  相似文献   

Growth of ringwoodite reaction rims from MgSiO3 perovskite and periclase at 22.5 GPa and 1,800 °C     

Akira Shimojuku  Asmaa Boujibar  Daisuke Yamazaki  Takashi Yoshino  Naotaka Tomioka  Junshan Xu 《Physics and Chemistry of Minerals》2014,41(7):555-567

The growth rate of ringwoodite reaction rims between MgSiO₃ perovskite and periclase was investigated at 22.5 GPa and 1,800 °C for 1–24 h using the Kawai-type high-pressure apparatus. The reaction was likely to proceed by a diffusion-controlled mechanism in which the dominant diffusion mechanism was grain-boundary diffusion. The reaction constant (the width of the ringwoodite reaction rim squared divided by time) determined from these experiments was between 1.3 × 10^?15 and 5.6 × 10^?15 m²/s. A Pt inert marker experiment indicated that the MgO component migrated faster than the SiO₂ component in ringwoodite. Thus, either Mg or O having the slower diffusion rate controlled the reaction. Because previous diffusion studies have shown that diffusion rates of O are slower than those of Mg, O would be a rate-controlling element for ringwoodite formation from MgSiO₃ perovskite and periclase. The growth rate appeared to be too fast to explain the observed topographic rise (~10 km) inside mantle plumes at the 660-km discontinuity.  相似文献   

Properties of host haloes of Lyman-break galaxies and Lyman α emitters from their number densities and angular clustering     

Takashi Hamana  Masami Ouchi  Kazuhiro Shimasaku  Issha Kayo  Yasushi Suto 《Monthly notices of the Royal Astronomical Society》2004,347(3):813-823

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