Evolution and effect of the stress concentration and rock failure in the deep multi-seam coal mining   总被引：1，自引：0，他引：1  

Mingwei Zhang  Hideki Shimada  Takashi Sasaoka  Kikuo Matsui  Linming Dou 《Environmental Earth Sciences》2014,72(3):629-643

Supports crushing accident occasionally occurs in the protected seam exploitation of deep multi-seam coal mining structure and results in adverse effect to the production. To prevent its recurrence in a newly developed working field, a 3D numerical extraction model was built based on the geologic and mining conditions of Jining coal mine to evolve the changes, state and characteristics of the reconstructed vertical and lateral stress in rock interlayer after protective seam exploitation. Stress release and increase zones of this mining structure were separated. Mining-induced localized stress concentration and the interlayer rock failure behavior were explored. The action of concentrated stress on the hydraulic supports in protected seam was discussed upon the major stress redistribution. Using the infinitesimal strain method, a mechanical model was created to further explore, from the vertical and lateral directions, the cause and mechanism of localized stress concentration and rock failure behavior in rock interlayer. The field investigation was finally performed to verify the numerical and mechanical results, and the essential control measures were proposed to prevent this accident. Key findings of this study bring some new insights into the deep multi-seam coal extraction and help to promote a more reliable underground mining.  相似文献   

Analysis of dust events in 2008 and 2009 using the lidar network, surface observations and the CFORS model     

Nobuo Sugimoto  Yukari Hara  Atsushi Shimizu  Tomoaki Nishizawa  Ichiro Matsui  Masataka Nishikawa 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(1):27-39

The Asian dust events in 2008 (May 24–June 4 in 2008) and in 2009 (March 12–25, October 13–26, and December 15–28 in 2009) were analyzed with the lidar network observations, surface observations in China, Korea, Japan, and Mongolia, and with the chemical transport model CFORS. Transport of Asian dust and mixing of dust with air pollution aerosols were studied. The event of May 24 to June 4 in 2008 was a significant event unusually late in the spring dust season. The dust event of March 12–25, 2009 was an interesting example of elevated dust layer, and transport of dust from the elevated dust layer to the ground by the boundary layer activity was observed with the lidars and surface observations in Japan. The concentration of air pollution aerosols was relatively high during the dust event, and the results suggest that vertical structure as well as transport path is important for the mixing of dust and air pollution aerosols. The dust events in October and December 2009 were examples of dust events in autumn and winter. The online mode CFORS reproduced the observation data generally well, except for the event of May 24 to June 4 in 2008. The results of the fourdimensional variational assimilation of the lidar network data reproduced the dust concentration in Korea and Japan reasonably in that event.  相似文献   

Experimental and Numerical Investigations of Ground Deformation Using Chemical Grouting for Pipeline Foundation     

Hideki Shimada  Yanlong Chen  Koichi Araki  Takashi Sasaoka  Kikuo Matsui 《Geotechnical and Geological Engineering》2012,30(2):289-297

Based on experimental and numerical investigations, the present paper focuses on under ground scope (UGS) chemical grouting method that can actually improve the pipeline surrounding foundation to solve pipeline saggy damage. According to the experimental results, a solution-type injection material could make lager soil deformation, using less total slurry amount than suspension-type injection material. Therefore, a suspension-type injection material with shorter gel time is more suitable for the UGS method, making it more effective to reinforce the pipeline foundation and restore pipelines. The results of some patterns of injection tests revealed relationship between the behavior of the grouting material and the deformation of the soil. It is found that the material can be injected into a foundation by fracture grouting if the permeation coefficient is lower than 1.00 × 10⁻³ mm/s. The situation was analyzed by using 2-D finite element method analysis software Phase2, and the analysis result proposes that the real data and simulation data are nearly the same in impermeable soil. Furthermore, even if the construction object is permeable soil, it can also be become impermeable soil by two phases grouting: soil improvement grouting and restoration grouting.  相似文献   

Subhorizontal tectonic framework of the Horoman peridotite complex and enveloping crustal rocks,south‐central Hokkaido,Japan     

Hiroshi Yamamoto  Natsumi Nakamori  Masaru Terabayashi  Hafiz Ur Rehman  Masahiro Ishikawa  Yoshiyuki Kaneko  Takashi Matsui 《Island Arc》2010,19(3):458-469

Geological observations in the Horoman area, south‐central Hokkaido, show that the Horoman peridotite complex of the Hidaka metamorphic belt is a tectonic slice about 1200 m thick. The peridotite slab is intercalated into a gently east‐dipping structure. The underlying unit is a Cretaceous–Paleogene accretionary complex. Riedel shear planes in the sedimentary layers of the accretionary complex near the structural bottom of the peridotite slab indicate top‐to‐the‐west (thrust) displacement. The overlying unit is composed of felsic–pelitic gneisses and mafic–felsic intrusive rocks (the Hidaka metamorphic rocks). The boundary surface between the peridotite complex and metamorphic rocks forms a domal structure. Microstructures of sheared metamorphic rocks near the structural top of the peridotite slab indicate top‐to‐the‐east (normal) displacement. The results combined with previous studies suggest that the Horoman peridotite complex was emplaced onto the Asian margin (Northeast Japan) during the collision between the Asian margin and the Hidaka crustal block.  相似文献   

Effects of disturbance of seawater excited by internal wave on GNSS-acoustic positioning     

Matsui  R.  Kido  M.  Niwa  Y.  Honsho  C. 《Marine Geophysical Researches》2019,40(4):541-555

Traditional Global Navigation Satellite System-Acoustic (GNSS-A) positioning assumes the Layered Model in the sound speed structure, and any of horizontal perturbation of seawater degrades its accuracy. However, the use of the Gradient Model analytically demonstrated that the horizontal gradient of the sound speed structure and displacement can simultaneously be solved using multiple transponders for each of ping. We applied this technique to our observed data and found it unsuitable for real data. We confirmed that a horizontal perturbation with wavelength shorter than the horizontal extent of the transponder array significantly violates the linear approximation in the Gradient Model. Our vertical 2D numerical simulation of internal waves (IWs) forced by tidal oscillation showed that such small-scale IWs could effectively be generated by nonlinear cascade from large-scale IWs of the major tidal constituents. In addition, a small-scale IW in deep water typically has a period of 3–4 h, which degrades positioning accuracy significantly, whereas an IW of much shorter period in shallow water has less effect after removal of the fluctuation by time averaging within a typical observation period. Apparent array position obtained in the synthetic test based on the simulated IW-derived sound speed structure showed features quite similar to that observed in real surveys. To incorporate such deeper perturbation, we proposed a Disturbance Model using dual sea surface platforms, that can solve time-varying perturbation in the vicinity of each transponder.

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Impacts of nutrient management and decrease in paddy field area on groundwater nitrate concentration: a case study at the Nasunogahara alluvial fan,Tochigi Prefecture,Japan     

Hiroaki Somura  Akira Goto  Hiroyuki Matsui  Elhassan Ali Musa 《水文研究》2008,22(24):4752-4766

In order to help evaluate the trends in the NO₃-N concentration in groundwater with a view to preventing further degradation in water quality in the future, a distributed groundwater quality model was constructed for the Nasunogahara basin. The best fit for the groundwater table elevations by the flow component of the model was achieved with average mean absolute errors (MAEs) of 0·92 m for the calibration period and 0·83 m for the validation period. Moreover, the best fit for the NO₃-N concentration by the water quality component was achieved with average mean relative errors (MREs) of 29·8% for the calibration period and 30·3% for the validation period. After developing a robust model, various change scenarios were tested; specifically, the effects of effluent load control and a decrease in paddy field area on the NO₃-N concentration in groundwater were predicted. The most intensively farmed area contributed about 40% of the total effluent load because of livestock farming in the basin. When the effluent load from this area was decreased by 50%, the average NO₃-N concentrations at sites S1, S2 and S3 were reduced by about 15%; however, the average concentrations at S4 and S5 were reduced by only 1%. Furthermore, when the total effluent load from the concentrated livestock area was removed completely, the average groundwater NO₃-N concentrations at S1, S2 and S3 were reduced by about 30% as compared with the original calculated results. In contrast, decreasing the area of the paddy fields in the basin did not greatly influence the groundwater NO₃-N concentration. In the case of a 70% reduction in paddy field area, average NO₃-N concentrations increased by about 7% at S1, S2 and S3. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Editorial     

A. Kavner  M. Matsui  C. McCammon  M. Rieder  T. Tsuchiya 《Physics and Chemistry of Minerals》2013,40(1):1-2

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Accretion process of the moon     

Hitoshi Mizutani  Takahumi Matsui  Hitoshi Takeuchi 《Earth, Moon, and Planets》1972,4(3-4):476-489

Recent geochemical and geophysical data suggest that the initial temperature of the Moon was strongly peaked toward the lunar surface. To explain such an initial temperature distribution, a simple model of accretion process of the Moon is presented. The model assumes that the Moon was formed from the accumulation of the solid particles or gases in the isolated, closed cloud. Two equations are derived to calculate the accretion rate and surface temperature of the accreting Moon. Numerical calculations are made for a wide range of the parameters particle concentration and particle velocity in the cloud. A limited set of the parameters gives the initial temperature profiles as required by geochemical and geophysical data. These models of the proto-moon cloud indicate that the lunar outershell, about 400 km thick, was partially or completely molten just after the accretion of the Moon and that the Moon should have been formed in a period shorter than 1000 yr. If the Moon formed at a position nearer to the Earth than its present one, the Moon might have been formed in a period of less than one year.On leave from Geophysical Institute, University of Tokyo.Contribution No. 2104, Division of Geological and Planetary Sciences, California Institute of Technology.  相似文献   

Latitudinal distribution of HDO abundance above Venus’ clouds by ground-based 2.3 μm spectroscopy     

H. Matsui  N. Iwagami  M. Hosouchi  S. Ohtsuki  G.L. Hashimoto 《Icarus》2012,217(2):610-614

The abundance of HDO above the clouds in the dayside atmosphere of Venus was measured by ground-based 2.3 μm spectroscopy over 4 days. This is the first HDO observation above the clouds in this wavelength region corresponding to a new height region. The latitudinal distributions found show no clearly defined structure. The disk-averaged mixing ratio is 0.22 ± 0.03 ppm for a representative height region of 62–67 km. This is consistent with measurements found in previous studies. Based on previous H₂O measurements, the HDO/H₂O ratio is found to be 140 ± 20 times larger than the telluric ratio. This lies between the ratios of 120 ± 40 and 240 ± 25, respectively, reported for the 30–40 km region by ground-based nightside spectroscopy and for the 80–100 km region by solar occultation measurement on board the Venus Express.  相似文献   

A hydrocode calculation coupled with reaction kinetics of carbon compounds within an impact vapor plume and its implications for cometary impacts on Galilean satellites     

Ryo Ishimaru  Hiroki Senshu  Takafumi Matsui 《Icarus》2010,210(1):411-423

The synthesis of organic molecules via chemical reactions within impact vapor plumes has been proposed as a mechanism to supply organics on a planet. However, the kinetics of chemical reactions within a rapidly expanding vapor plume or quenching process of the reactions has not been studied extensively. In this study, we constructed a new numerical model that calculates kinetics of the entire chemical reactions within an impact vapor plume. Numerical results revealed that the semi-analytical models proposed so far, in which the final amount of a chemical species was given by the equilibrium abundance at the quenching temperature of the fastest reaction path involving the species, underestimates the yield of organic molecules, such as HCN, by up to a factor of 10. This is because the previously used assumption that a species can achieve equilibrium with the rest of the reaction system via the fastest reaction path involving the species is not necessarily valid. Our analysis of the high-temperature H/C/N/O reaction system suggests that the quenching of slow reactions divides the reaction network into smaller reaction sub-systems isolated from the rest of the reaction system. Then, the fastest reaction path cannot equilibrate an isolated reaction sub-system with the rest of the reaction system. Simulation of this actual disequilibrium mechanism requires a simultaneous numerical calculation of the entire reaction network, which is equivalent to conducting a full kinetic model calculation, such as our model. Our numerical code makes it possible to discuss quantitatively the impact chemistry for various situations, such as the Galilean satellites. In this study, our numerical model is applied to the delivery of organic molecules via cometary impact on the Galilean satellites. Our numerical results indicate that small-particle impacts would produce HCN efficiently. Resulting HCN may freeze out immediately and be deposited on satellite surfaces, where it may be eventually converted into complex organics via irradiation of charged particle. On the other hand, large-size impacts may form transient CH₄-N₂ atmospheres, in which complex organics (tholin) may be formed via energy deposition of UV and/or charged particle. Resulting complex organics may subsequently precipitate on the satellite surfaces without clear correlation with the locations of impact craters. Such distribution of complex organics created by chemical reactions within vapor plumes due to cometary impacts may explain an absorption (4.57 μm) on Galilean satellites nonassociated with observable (moderate- and large-size) impact craters.  相似文献