※一部利用できない機能があります
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西川 , 隼人 ; 高谷 , 富也 ; 釣 , 健孝 ; 福井 , 繁雄 ; 宮島, 昌克 ; Nishikawa, Hayato ; Takatani, Tomiya ; Tsuri, Takeyoshi ; Miyajima, Masakatsu
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We develop vibration measuring equipment using high accurate inclimeter sensor that was not used in the past studies rel
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ated to MEMS sensor. Since high accurate inclimeter sensor has higher resolution and lower self-noises than general MEMS sensors, it is able to measure slighter vibration than the MEMS sensors. In order to examine performance of the equipment developed in this study, vibration characteristics of wooden house is investigated by measurement by using the equipment and servo type accelerometer. Natural frequencies of Fourier spectra of acceleration waves measured by this equipment are mostly corresponded to that measured by the servo type accelerometer. Moreover, natural frequencies of transfer function evaluated by servo type accelerometer are close to those of Fourier spectra.<br />本研究では，これまでのMEMSセンサに関する研究で用いられていない高精度傾斜センサによる振動測定装置を試作した．高精度傾斜センサは一般的なMEMSセンサと比べて分解能が高く，自己ノイズも小さいため，従来よりも小さな振動を測定することができる． 試作した振動測定装置の性能を調べるためにサーボ型加速度計とともに，木造建物の常時微動を測定し，加速度フーリエスペクトルから建物の振動特性を評価した．これらの装置の計測波形から求めたフーリエスペクトルの固有振動数は概ね一致した．また，サーボ型加速度計で評価した伝達関数の固有振動数はフーリエスペクトルの固有振動数と近い値となった．
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Amiraslanzadeh, Reza ; Ikemoto, Toshikazu ; Miyajima, Masakatsu
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池本 , 敏和 ; 森, 雅士 ; 宮島, 昌克 ; 橋本, 隆紀 ; 村田, 晶 ; Ikemoto, Toshikazu ; Mori, Masashi ; Miyajima, Masakatsu ; Hashimoto, Takanori ; Murata, Akira
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金沢大学理工研究域地球社会基盤学系<br />日本では，地震による間知ブロック積み擁壁の被害が多発している．そこで，間知ブロック積み擁壁の振動特性と破壊機構に関する実験的研究を行った．実験データは加速度による応答倍率，変位，土圧を測定した．
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擁壁は振動によって，盛土の沈下が発生し擁壁中部から破壊することがわかった．<br />There are many earthquake damages of kenchi block masonry wall. So, we carried out experimental studies on the collapse mechanism of kenchi block masonry wall during earthquake. From these experimental data, i.e. acceleration response magnification, displacement and soil pressure were found to destroy the central wall vibrations caused by the subsidence of the embankment.
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Sun, Hong ; Miyajima, Masakatsu ; Qiao, Lei
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Murata, Akira ; Kitaura, Masaru ; Miyajima, Masakatsu
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Achour, Nebil ; Miyajima, Masakatsu ; 宮島, 昌克
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金沢大学理工研究域地球社会基盤学系<br />The Japanese Prefecture of Kumamoto experienced a series of strong earthquakes in April 2016 caus
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ing widespread damage and had a serious impact on local communities. The events caused over 3000 casualties and affected the continuity of healthcare services. Many hospitals had to be evacuated but the reasons for this evacuation are not clear. This research aims to investigate the impact of damage on the performance of the healthcare service through a survey of 118 healthcare facilities. The study connects earthquake metrics and the loss of healthcare service functionality and reveals the reasons for which facilities were totally or partially evacuated. Findings suggest that the reasons are mainly damage to buildings, critical systems, and medical equipment. It concludes by estimating that the stricken areas lost approximately 15% of their healthcare functionality. The study also concludes that the current building standards increased the performance of hospital buildings by approximately 10%; however, more attention is needed to protect architectural and critical systems. © The Author(s) 2020.
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Miyajima, Masakatsu ; Setiawan, Hendra ; Yoshida, Masahiro ; Ono, Yusuke ; Kosa, Kenji ; Oktaviana, Ida Sri ; Martini ; Irdhiani ; 宮島, 昌克
概要:
金沢大学理工研究域地球社会基盤学系<br />BackgroundOn September 28th, 2018, at 18:02 local time (10:02 UTC), a strong earthquake of magnit
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ude Mw = 7.5 struck Central Sulawesi Province, Indonesia. The epicenter was located at 0.256o south latitude and 119.846o east longitude, around 77 km from Palu city, and 20 km below the ground surface. To understand the damage caused by the earthquake, and find a solution to mitigate the geo-disasters in Indonesia, a preliminary investigation on the 2018 Sulawesi earthquake was conducted from 16 to 20 November 2018. This quick report focuses on ground displacements induced by fault movement and large-scale ground flow.ResultsDuring the survey, there is some geotechnical damage were found, such as ground displacement induced by fault movement, liquefaction, landslides, and large-scale ground flow in some certain areas. Large ground displacement was found in some particular areas, such as Kedondong, Pipa Air, Pangeran Diponegoro and Cemara streets in Palu city. The earthquake also triggered large-scale ground flow in some different sites, such as Balaroa and Petobo districts in Palu city and Jono Oge and Sibalaya Villages.ConclusionsThe locations of large ground displacements appeared at surface coincide well with the estimated fault line. Therefore the large ground displacements were seems to be induced by the fault movement. Large ground flow caused severe damage to not only human but also houses and buildings. The mechanism of the large ground flow should be clarified in near future.
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Wang, Fawu ; Miyajima, Masakatsu ; Dahal, Ranjan ; Timilsina, Manita ; Li, Tonglu ; Fujiu, Makoto ; Kuwada, Yohei ; Zhao, Quanli ; 宮島, 昌克 ; 藤生, 慎
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金沢大学理工研究域地球社会基盤学系<br />BackgroundThe 2015.4.25 Gorkha earthquake affected about eight million people in Nepal. Most inju
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ries and loss of life were due to building collapse and damage. This work aims to investigate the topographical and geological effects on the severe damage caused by this earthquake.FindingsIn one-week field investigation in the earthquake-affected areas, several severely damaged areas with different topographic and geological features were surveyed, as well as the site of Kaligandaki River landslide dam failure. Some general tendency related to the building damage and landslide dam failure was obtained.ConclusionsThrough the field investigation, it was found that geological and geomorphological characteristics of a site, combined with the structure feature of the building, such as the short column effect, amplified the seismic vibration and caused severe building collapse and damages, i.e., 1) For buildings on flat area consisting of lacustrine deposit or diluvial deposit, resonance effect might be the main reason, while for the buildings on the top of hills or narrow ridges, topographic effect and sometimes, short column effect should take the main responsibility; 2) For buildings located on the gentle slopes or landslides, the settlement in the infill side caused by the strong seismic vibration can be the main reason; 3) Besides of the building failure on lacustrine deposit, failure patterns in three types of topographic and geological features, i.e., narrow ridges formed by landslides, diluvial deposits and alluvial fans, and landslides, were proposed as the possible mechanism of the building damage caused by the earthquake. For landslide dam failure, it was found that landslide dam could easily breach or collapse, when the landslide-dam-deposits were fine.
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Setiawan, Hendra ; Serikawa, Yuko ; Sugita, Wataru ; Kawasaki, Hajime ; Miyajima, Masakatsu ; 宮島, 昌克
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金沢大学理工研究域地球社会基盤学系<br />BackgroundEarthquakes in liquefaction-prone areas are frequently followed by the settlement of su
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rface structures due to subsoil liquefaction. This paper aims to study the influence of geosynthetics along with gravel usage to reduce the vertical soil displacement caused by liquefaction using a shake table equipment. This influence is analyzed by means of measuring soil acceleration, pore water pressures and vertical soil deformation due to the shaking process.ResultsResults of a series of 1-g shaking table tests which have been conducted in different initial relative densities which are 50% (loose sand conditions) and 90% (dense sand conditions) to evaluate the performance of proposed mitigation against settlement problem are presented. It is found that ground settlement reduced around 11.4 mm for loose sand conditions, from 20.9 mm in the case with no countermeasure (Case 1) to 9.5 mm in the Case reinforced with gravel and geosynthetics Type II (Case 4). Correspondingly, for dense sand states, the settlement decreased by about 1.8 mm, from 5.6 mm in the Case 1 to 3.8 mm in Case 4. Moreover, a differential settlement between loose sand and dense sand conditions decreased as well, around 9.6 mm, from 15.3 mm in the Case 1 to 5.7 mm in Case 4.ConclusionsBy conducted a series of shake table tests, it is confirmed that the vertical ground displacement decreased by the use of geosynthetics and gravel up to 54% and 32% for loose sand and dense sand states, respectively. Furthermore, test results also show that there is a decrease in the differential settlement between loose sand and dense sand conditions, around 62%.
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Serikawa, Yuko ; Miyajima, Masakatsu ; Yoshida, Masaho ; Matsuno, Kenji ; 宮島, 昌克
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金沢大学理工研究域地球社会基盤学系<br />BackgroundOn September 6th, 2018, at 3:07 local time, a strong earthquake of magnitude Mw = 6.6 s
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truck the east Iburi region in Hokkaido, Japan. Many serious damages such as landslide, liquefaction and collapse of houses occurred from this earthquake. Liquefaction caused road deformation and inclination of houses in Sapporo city, Hokkaido. In order to understand the damage caused by the earthquake, and find a solution to mitigate the liquefaction-induced damage in Sapporo city, a preliminary investigation of the 2018 Hokkaido Iburi-tobu earthquake was conducted from 18 to 20 September 2018.ResultsThe damages to the houses at Satozuka town and Utsukushigaoka town in Sapporo city are focused on. The damage at Satozuka was so enormous that the residents could not continue to live in their houses. Although the inclination of houses can be seen by visual inspection at Satozuka, there were few houses where the inclination can be judged visually at Utsukushigaoka. Therefore we did a field survey of inclined houses by using a digital angle meter at Utsukushigaoka.ConclusionsThe inclination of 57 houses at Utsukushigaoka was measured, and the maximum value and direction of inclination are shown on the map. The houses located at the reclaimed land of the former river and former valley plain were inclined. Therefore, the old terrain greatly affected to the inclination of houses. These liquefaction-induced damage occurred in the same area where liquefaction occurred during the 2003 Tokachi-oki earthquake.
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