Performance-based analysis and design for internal stability of MSE walls     

Richard J. Bathurst  Tony M. Allen  Yoshihisa Miyata  Sina Javankhoshdel  Nezam Bozorgzadeh 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2019,13(3):214-225

ABSTRACT

Mechanically stabilized earth (MSE) walls must be designed with adequate margins of safety against internal stability failure described by tensile strength and pullout limit states. Probabilities of failure (or reliability index) will vary strongly with the accuracy of the underlying models that appear in limit state performance functions. In this paper, prior work by the authors and co-workers on this topic is reviewed. Relative performance is explored in the context of the reliability (or probability of failure) of steel and polymeric reinforcing elements in MSE walls using limit state performance functions with load and resistance models having different accuracy.  相似文献   

Regional landslide susceptibility following the Mid NIIGATA prefecture earthquake in 2004 with NEWMARK’S sliding block analysis   总被引：1，自引：0，他引：1  

Masahiro Shinoda  Yoshihisa Miyata 《Landslides》2017,14(6):1887-1899

This study proposes a calculation method for regional earthquake-induced landslide susceptibility that applies the permanent seismic displacement calculated using Newmark’s sliding block analysis with estimated vertical and horizontal seismic motions. The proposed method takes into account the direction of slope failure based on the specified slope azimuth. The study results reveal the importance of predominant slope failure direction using a simple infinite slope model subjected to earthquakes. The target area for the earthquake-induced landslide susceptibility analysis constituted a region of more than 2000 km² surrounding the epicenter of the Mid Niigata prefecture earthquake in 2004. An earthquake-induced landslide susceptibility map was created based on the proposed method with a specific combination of friction angle and cohesion, and the resulting data were compared to the landslide inventory map produced from aerial photographs following the Mid Niigata prefecture earthquake in 2004. To create the susceptibility map, geomaterial cohesion values for the slope were back-calculated to satisfy the minimum safety factor in the static state. This study also proposes a calculation method for the prediction rate and determines the back-calculated strength parameters of geomaterials. The proposed regional landslide susceptibility map will be useful for understanding potential slope failure locations and magnitude of damage, as well as for planning field investigation and preventing secondary disasters immediately after earthquakes.  相似文献   

Seismic subsidence near the source region of the 1662 Kanbun Hyuganada Sea earthquake: Geochemical,stratigraphical, chronological,and paleontological evidences in Miyazaki Plain,southwest Japan     

Masakazu Niwa  Takanobu Kamataki  Hideki Kurosawa  Yoko Saito‐Kokubu  Masafumi Ikuta 《Island Arc》2020,29(1)

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Integrated field spectroscopy of E+A (post-starburst) galaxies with the Kyoto tridimensional spectrograph II     

Tomotsugu Goto  Atsushi Kawai  Atsushi Shimono  Hajime Sugai  Masafumi Yagi  Takashi Hattori 《Monthly notices of the Royal Astronomical Society》2008,386(3):1355-1365

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Four-dimensional variational ocean reanalysis: a 30-year high-resolution dataset in the western North Pacific (FORA-WNP30)     

Norihisa Usui  Tsuyoshi Wakamatsu  Yusuke Tanaka  Nariaki Hirose  Takahiro Toyoda  Shiro Nishikawa  Yosuke Fujii  Yasushi Takatsuki  Hiromichi Igarashi  Haruka Nishikawa  Yoichi Ishikawa  Tsurane Kuragano  Masafumi Kamachi 《Journal of Oceanography》2017,73(2):205-233

We produced a four-dimensional variational ocean re-analysis for the Western North Pacific over 30 years (FORA-WNP30). It is the first-ever dataset covering the western North Pacific over 3 decades at eddy-resolving resolution. The four-dimensional variational analysis scheme version of the Meteorological Research Institute Multivariate Ocean Variational Estimation system (MOVE-4DVAR) is employed to conduct a long-term reanalysis experiment during 1982–2012. After evaluating the basic performance of FORA-WNP30, the interannual to decadal variability is analyzed. Overall, FORA-WNP30 reproduces basic features in the western North Pacific well. One of outstanding features in FORA-WNP30 is that anomalous events such as the Kuroshio large meander and anomalous intrusion of the Oyashio in the 1980s, when there were no altimeter data, are successfully reproduced. FORA-WNP30 is therefore a valuable dataset for a variety of oceanographic research topics and potentially for related fields such as climate study, meteorology and fisheries.  相似文献   

The impact of faults on the geomorphology of the Earth’s crust: case study of faults impacts on the geomorphology of Lar Valley,Northeast of Tehran (Iran)     

A. Khorsandi  T. Miyata 《Environmental Geology》2009,57(3):583-590

The geomorphology of the Lar Valley in the Northeast of Tehran, the Capital of Iran, is under the geological influence of the Central Alborz, in which the different geological formations are folded and thrust, time and again over each other by faults, creating the heights. The Damavand volcano is located to the east of Lar Valley, appearing in the heights of Alborz at the point of deviation in the structural strike of Alborz chain and along the faults during the quaternary period. The physiographic, landslide phenomenon, rock fall, valleys, water courses and alluvial fans in the Lar Valley were reviewed and studied according to aerial photographs, satellite images and field observations from the aspect of their susceptibility to the impact of faults. The results indicate that 80% of the peaks and high mountains in Lar Valley are created and influenced by the action of overthrust faults. Ninety percent of the land and rock sinking are located in the intermediate regions between the faults, and they are believed to be the results of fault impacts. Seven out of the nine cases of landslide in Lar are located on or in the margin of the faults depicting the latter’s influence. The floor ratios of eight valleys were calculated and it was determined that in addition to the impacts of faults on creating the valleys, the situation of most of these along the margins of the faults as well as seven valleys are influenced by faults. The slope of rivulets and auxiliary rivers and their angles in relation to each other and the main river were calculated. The results showed that seven rivulets were under the influence of faults. Fifty-nine percent of the alluvial fans in Lar Valley were greatly influenced by faults, whereas 49% were under their normal impact. The supposition in this study is that the results can be used to identify faults and their characteristics.  相似文献   

含有开关参数化物理过程的模式变分资料同化的非光滑优化方法:几个理论问题   总被引：7，自引：0，他引：7  

Zhu Jiang  Masafumi Kamachi  Zhou Guangqing 《大气科学进展》2002,19(3):405-424

时间、空间上离散的模式如果含有带开关的参数化物理过程，某些对应的变分同化问题可以看成为非光滑优化问题。本系统地讨论了与此相关的几个理论问题。首先，利用次梯度这个非光滑优化中的基本概念可以对通常的伴随方程的解进行清楚的解释和定义。利用一个带对流调整的多层扩散模式，演示了通常的伴随方程的解在奇异点处不是由代价函数的Gateaux导数构成，而是代价函数的一个次梯度。其次，在非光滑优化的框架下对现有的解决这类问题的方法进行了评述。这些方法包括：（1）利用光滑优化方法和通常的伴随模式，并且讨论了这个方法的收敛条件；（2）正则化方法。这个方法是把模式中不光滑的项用光滑的项近似，以把问题变为光滑优化问题。（3）次梯度方法。这个方法利用通常的伴随模式来计算一个次梯度，是收敛的算法，不过收敛速度很慢。（4）非光滑优化中的Bundle方法。这个方法比次梯度方法收敛得快，不过需要利用所有的次梯度信息。由于计算所有的次梯度十分困难，现有的Bundle方法大都进行了一些改变，仅需要用户能够计算出一个次梯度。不过这个改变是无奈的，多个次梯度的信息可以提高Bundle方法的效率。本最主要的工作是提出了集值伴随方程的概念。集值伴随模式可以在奇异点处计算出所有支撑次梯度，因此利用集值伴随方程有可能提出基于Bundle方法的更好算法。  相似文献   

A Study of Tsunami Wave Fission in an Undistorted Experiment     

Masafumi Matsuyama  Masaaki Ikeno  Tsutomu Sakakiyama  Tomoyoshi Takeda 《Pure and Applied Geophysics》2007,164(2-3):617-631

To study tsunami soliton fission and split wave-breaking, an undistorted experiment was carried out which investigated tsunami shoaling on a continental shelf. Three models of the continental shelf were set up in a 205-m long 2-dimensional flume. Each shelf model was 100 m, long with slopes of either 1/100, 1/150, or 1/200. Water surface elevations were measured across the flume, including a dense cluster of wave gages installed around the point of wave-breaking. We propose new methods for calculating wave velocity and the wave-breaking criterion based on our interpretation of time series data of water surface elevation. At the point of wave-breaking, the maximum slope of water surface is between 20 to 50 deg., while the ratio of surface water particle horizontal velocity to wave velocity is from 0.5 to 1.2. The values determined by our study are larger than what has been reported by other researchers.  相似文献   

Seasonality of the Kuroshio Transport Revealed in a Kuroshio Assimilation System   总被引：2，自引：2，他引：2  

Atsuhiko Isobe  Masafumi Kamachi  Yukio Masumoto  Hiroshi Uchida  Tsurane Kuragano 《Journal of Oceanography》2004,60(2):321-328

The seasonal variation of the Kuroshio transport south of Japan has been investigated using the results of an assimilation model. Annual and semiannual variations of the transport and dynamic depth anomaly are reconstructed by CEOF (complex orthogonal empirical function) analysis. In the basin west of the Izu-Ogasawara Ridge, the annual component of the variation propagates westward with the phase speed of the long Rossby wave associated with the first baroclinic mode. The variation also shows a similar tendency to that reproduced in a wind-driven, two-layer model with a ridge. This suggests that the annual variation revealed in the assimilation model is associated with the baroclinic first mode of motion excited above the Izu-Ogasawara Ridge. Furthermore, it is found that both the semiannual component and the annual component are important members determining the seasonal variation of the Kuroshio transport south of Japan. The semiannual component is revealed as a double gyre pattern in the basin west of the Izu-Ogasawara Ridge. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Interannual and Decadal Variabilities of NPIW Salinity Minimum Core Observed along JMA’s Hydrographic Repeat Sections     

Toshiya?NakanoEmail author  Ikuo?Kaneko  Masahiro?Endoh  Masafumi?Kamachi 《Journal of Oceanography》2005,61(4):681-697

We investigated the variation of the North Pacific Intermediate Water (NPIW) distribution in the western North Pacific, focusing on the intermediate salinity minimum (S < 34.2) core observed along the meridional hydrographic sections including the 137°E repeat section by the Japan Meteorological Agency. This core is a cross-section of a low salinity tongue extending westward along the recirculation in the subtropical gyre. The core size shows remarkable variabilities in interannual and decadal time scales. The salinity change in the density layer during the period of core expansion (shrinking) represents the spatial salinity change in the tongue toward the west (east). Thus, we conclude that the core size variation is associated with the zonal wobble of the tongue having thicker distribution to the east, rather than temporal changes of the water mass itself. The core size at 137°E is well correlated with the meridional gradient of the depth in the isopycnal surface at the salinity minimum representing the recirculation intensity, suggesting a relation with the intensity of the subtropical gyre. A significant lag-correlation between the gradient and the wind forcing over the North Pacific suggests that the first mode baroclinic Rossby waves excited in the central North Pacific propagated westward to change the intensity of the recirculation in interannual time scales. In decadal time scales, it is found that the wind stress curl and heat flux fields in the North Pacific precede the recirculation by about 11 years.  相似文献