Numerical analysis on seepage failures of dike due to water level-up and rainfall using a water–soil-coupled smoothed particle hydrodynamics model     

Weijie Zhang  Kenichi Maeda  Hiroshi Saito  Zhaoqing Li  Yu Huang 《Acta Geotechnica》2016,11(6):1401-1418

For seepage failures of dike due to water level-up and rainfall, surface infiltration and strength change induced by suction reduction are important factors; thus, numerical analysis should consider the coupling of water and soil, as well as the effect of saturation to obtain more precise failure mechanism. Based on the advanced smoothed particle hydrodynamics (SPH) method, this work proposed a two-phase-coupled SPH model in coordination with a novel constitutive model for unsaturated soils. Then, a triaxial compression test is simulated to check the applicability of the SPH method on the soil phase. After that, the failure test of a dike due to water level-up is discretized and simulated, from which the seepage process, the distribution of maximum shear strain, the slip surface, and pore water pressure are obtained. The two-phase-coupled SPH model is also applied to a slope failure test of heavy rainfall, and the results are compared to the model test. Finally, a dike failure test due to rainfall is analyzed using the proposed SPH model to reproduce the surface infiltration and suction reduction. The proposed SPH model provides several insights of seepage failures and can be a helpful tool for the analysis of dike failures induced by water level-up and rainfall.  相似文献   

Use of Statistical Models to Analyze Periodic Seismicity Observed for Clusters in the Kanto Region, Central Japan     

M. Imoto  K. Maeda  A. Yoshida 《Pure and Applied Geophysics》1999,155(2-4):609-624

—A periodic pattern of seismicity has been reported for the Kinugawa cluster in the Kanto region, where several earthquake clusters are observed at depths between 40 and 90 km. To analyze this periodicity, statistical studies are performed for the Kinugawa cluster together with eight other clusters. Hypocentral parameters of the earthquakes with magnitudes 4.5 and larger for the period between 1950 and 1995 are taken from the JMA catalogue. The simple sinusoidal function, the exponential of sinusoidal function and the stress release model are applied as the intensity function. Model parameters are determined by the maximum likelihood method and the best model for each cluster is selected by using the Akaike Information Criterion (AIC). In six cases the sinusoidal model or the exponential of the sinusoidal model is selected as the best option and achieves AIC reductions of values between 2.4 and 13.2 units from the simple Poisson model. The stress release model is selected for two clusters. The three clusters, the Kinugawa, Kasumigaura, and Choshi clusters, have a similar optimal period of about 10 years, and align in the northwest–southeast direction at a similar depth range of 40 to 70 km. A model modified from the stress release model is applied to the three clusters so to analyze the relationship among them. In the modified model, an earthquake occurrence in one zone increases the stress in the other zone, which is different from the original stress release model which assumes a linear increase with time. Applying the modified model to the Kinugawa cluster, an AIC reduction from the Poisson model is significantly larger than the value obtained with the sinusoidal model. This suggests that the periodic seismicity observed for the Kinugawa cluster can be explained with the more comprehensive model than the sinusoidal model.  相似文献   

Time Distribution of Immediate Foreshocks Obtained by a Stacking Method   总被引：1，自引：0，他引：1  

K. Maeda 《Pure and Applied Geophysics》1999,155(2-4):381-394

—We apply a stacking method to investigate the time distribution of foreshock activity immediately before a mainshock. The foreshocks are searched for events with M≥ 3.0 within a distance of 50 km and two days from each mainshock with M≥ 5.0, in the JMA catalog from 1977 through 1997/9/30. About 33% of M≥ 5.0 earthquakes are preceded by foreshocks, and 50–70% in some areas. The relative location and time of three types of representative foreshocks, that is, the largest one, the nearest one to the mainshock in distance, and the nearest one in time, are stacked in reference to each mainshock. The statistical test for stacked time distribution of foreshocks within 30km from and two days before mainshocks shows that the inverse power-law type of a probability density time function is a significantly better fit than the exponential one for all three types of representative foreshocks. Two explanations possibly interpret the results. One is that foreshocks occur as a result of a stress change in the region, and the other one is that a foreshock is the cause of a stress change in the region and it triggers a mainshock. The second explanation is compatible with the relationship between a mainshock and aftershocks, when an aftershock happens to become larger than the mainshock. However the values of exponent of the power law obtained for stacked foreshocks are significantly smaller than those for similarly stacked aftershocks. Therefore the foreshock–mainshock relation should not be explained as a normal aftershock activity. Probably an increase of stress during foreshock activity results in apparently smaller values of the exponent, if the second explanation is the case.  相似文献   

Crustal structure of central Japan and its petrological implications     

Oguz Ozel  Takaya Iwasaki  Takeo Moriya  Shin'ichi Sakai  Takuya Maeda  Chengshi Piao  Toshikatsu Yoshii  Shinya Tsukada  Akihito Ito  Masayuki Suzuki  Akira Yamazaki  & Hiroki Miyamachi 《Geophysical Journal International》1999,138(1):257-274

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Nebular emission-line profiles of Type Ib/c supernovae – probing the ejecta asphericity     

S. Taubenberger  S. Valenti  S. Benetti  E. Cappellaro  M. Della Valle  N. Elias-Rosa  S. Hachinger  W. Hillebrandt  K. Maeda  P. A. Mazzali  A. Pastorello  F. Patat  S. A. Sim  M. Turatto 《Monthly notices of the Royal Astronomical Society》2009,397(2):677-694

In order to assess qualitatively the ejecta geometry of stripped-envelope core-collapse supernovae (SNe), we investigate 98 late-time spectra of 39 objects, many of them previously unpublished. We perform a Gauss-fitting of the [O  i ]  λλ6300, 6364  feature in all spectra, with the position, full width at half maximum and intensity of the  λ6300  Gaussian as free parameters, and the  λ6364  Gaussian added appropriately to account for the doublet nature of the [O  i ] feature. On the basis of the best-fitting parameters, the objects are organized into morphological classes, and we conclude that at least half of all Type Ib/c SNe must be aspherical. Bipolar jet models do not seem to be universally applicable, as we find too few symmetric double-peaked [O  i ] profiles. In some objects, the [O  i ] line exhibits a variety of shifted secondary peaks or shoulders, interpreted as blobs of matter ejected at high velocity and possibly accompanied by neutron-star kicks to assure momentum conservation. At phases earlier than ∼200 d, a systematic blueshift of the [O  i ]  λλ6300, 6364  line centroids can be discerned. Residual opacity provides the most convincing explanation of this phenomenon, photons emitted on the rear side of the SN being scattered or absorbed on their way through the ejecta. Once modified to account for the doublet nature of the oxygen feature, the profile of Mg  i ]  λ4571  at sufficiently late phases generally resembles that of [O  i ]  λλ6300, 6364  , suggesting negligible contamination from other lines and confirming that O and Mg are similarly distributed within the ejecta.  相似文献   

Experiment and Theoretical Study of Earthquake Detection Capability by Means of Microwave Passive Sensors on a Satellite     

Takano  T. Maeda  T. 《Geoscience and Remote Sensing Letters, IEEE》2009,6(1):107-111

This letter presents the possibility of detecting earthquakes (EQs) from microwaves emitted when rock fractures. The method is based on an experiment in which microwave emission was detected from rock fracturing in a laboratory for the first time in the world. First, the method of calibrating emitted microwave power from experimental data is presented. A model of microwave emission and propagation to a satellite is then proposed. An advantage of microwaves is that they penetrate the Earth's ionosphere, unlike radiowaves of frequencies lower than several tens of megahertz. The power received by a satelliteborne receiver is estimated by assuming parameters of a radiometer currently operating in orbit. The result indicates that a satelliteborne receiver can detect microwave signals generated by an EQ. Based on this result, we attempted to detect some features associated with an actual EQ from the data of the Advanced Microwave Scanning Radiometer for Earth Observation System aboard the remote sensing satellite Aqua.  相似文献   

V-1 Optimum design method of OWC device     

Hisaaki Maeda 《Ocean Engineering》1985,12(6):579

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Notes on extended–range atmospheric prediction in the Northern Hemisphere winter     

Shingo Yama  Shuhei Mae  K. Gambo 《大气科学进展》1997,14(1):23-40

We examined the characteristic feature and predictability of low frequency variability (LFV) of the atmosphere in the Northern Hemisphere winter (January and February) by using the empirical orthogonal functions (EOFs) of the geopotential height at 500 hPa. In the discussion, we used the EOFs for geostrophic zonal wind (Uznl) and the height deviation from the zonal mean (Zeddy). The set of EOFs for Uznl and Zeddy was denoted as Uznl-1. Uznl-2, …, Zeddy-1, Zeddy-2…, respectively. We used the data samples of 396 pentads derived from 33 years of NMC, ECMWF and JMA analyses, from January 1963 to 1995. From the calculated scores for Uznl-1, Uznl-2, Zeddy-1, Zeddy-2 and so on we found that Uznl-1 and Zeddy-1 were statistically stable and their scores were more persistent than those of the other EOFs. A close relationship existed between the scores of Uznl-1 and those of Zeddy-1 30-day forecast experiments were carried out with the medium resolution version of JMA global spectral model for 20 cases in January and February for the period of 1984-1992. Results showed that Zeddy-1 was more predicta?ble than the other EOFs for Zeddy Considering these results, we argued that prediction of the Zeddy-1 was to be one of the main target of extended range forecasting  相似文献   

IV-4 On absorbed power from irregular waves by wave power devices     

Hisaaki Maeda  Takeshi Kinoshita 《Ocean Engineering》1985,12(6):578

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Fluctuation in volume transport distribution accompanied by the Kuroshio front migration in the Tokara Strait   总被引：1，自引：0，他引：1  

Akio Maeda  Toru Yamashiro  Masahito Sakurai 《Journal of Oceanography》1993,49(2):231-245

A relation between migration of the Kuroshio front and fluctuation of distribution of volume transport in the Tokara Strait was described, using sea level records at five tide gauge stations around the strait and data which were composed of sea surface temperature, XBT casts, sea surface salinity and velocities at 20 m, 75 m and 150 m depths taken en route a ferryboat. The Kuroshio front extends to about 150 m depth. The sea surface salinity and the horizontal velocities abruptly change at the front. There is a good correlation in a period range from half a month to two months between the migration of the front, which is not only at the surface but also in the subsurface, and the sea level fluctuation at Nakano-shima. A northward migration of the front with a period range from 17 to 50 days decreases the transport in the southern strait between Naze and Nakano-shima but increases in the northern strait between Nakano-shima and Sata-misaki. The northward migration intensifies inflow into Kagoshima Bay and the Ohsumi Branch Current. Correlation between the transport in the northern strait and the Ohsumi Branch Current is significant in the period range from 30 to 50 days. In this significant period range, the former leads the latter by about 3 days.  相似文献