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Abstract An earthquake accompanied by a huge tsunami will wash away not only structures but also many people, leading to an increase in missing people and deaths. It is important to know how the tsunami victims were washed away in order to strengthen tsunami countermeasures in the future. In this study, we reproduced the drifting behavior using numerical simulations for humans and showed that the drifting behavior offshore can be qualitatively expressed. The presented method is likely to be used for the estimation of tsunami driven drifting victims. Introduction Japan is one of the most earthquake-prone countries in the world and has been damaged by earthquakes and tsunamis many times in the past. A magnitude 9.0 earthquake with an epicenter off Sanriku occurred at around 14:46 on March 11, 2011, causing enormous earthquakes and tsunami damage mainly in eastern Japan. The tsunami caused by this earthquake caused not only flooding but also secondary damage caused by the collapse of houses, the generation of debris, and the drifting of vehicles, containers, and ships. The 2011 Tohoku-oki earthquake is a disaster with different characteristics from the 1923 Great Kanto Earthquake and the 1995 Great Hanshin-Awaji Earthquake. First, the earthquake destroyed the bedrock 400km north-south and 200km east-west off Ibaraki prefecture from Iwate prefecture, and the damage was particularly severe mainly in Iwate prefecture, Miyagi prefecture, and Fukushima prefecture. Great damage has also occurred in Aomori, Ibaraki, and Chiba prefectures. A huge tsunami occurred, and the disaster areas 500km north and south are scattered in the inner part of the bay on the ria coast, and the damage is various. Second, more than 90% of the victims died in the Tohoku-oki earthquake due to being involved in the tsunami. Many bodies have been found far away from their place of residence. On the other hand, most of the causes of death of the victims in the 1995 Great Hanshin-Awaji Earthquake were suffocation and crushing death due to the underlay of a collapsed house (The White Paper on Police, 2012).
Okabayashi, Kojiro (Architecture Kosen Institute of Technology) | Hashimura, Genki (Architecture Kosen Institute of Technology) | Okubo, Akari (Architecture Kosen Institute of Technology) | Ogasawara, Hyo (Architecture Kosen Institute of Technology)
ABSTRACT In the near future, the Nankai Trough earthquake is expected to occur in Japan. It may not be received by the rescue and support from the land in the event of a disaster since the Kochi Prefecture is surrounded by steep mountains. Therefore, Kochi Prefecture has placed earthquakeproof berth, but we propose that fishing ports also be used as disaster prevention bases. In this study, we investigated the liquefaction countermeasures for fishing port quay using sheet piles. As a result, ①It finds out that the construction method using sheet piles is not enough for liquefaction countermeasures. ②The method using sandbags and permeable steel sheet piles confirmed the effect of suppressing liquefaction. INTRODUCTION The Pacific coast of Tohoku Earthquake on March 11, 2011 is the largest earthquake in the observation history around Japan, caused huge damage by tsunami and liquefaction. All port of Pacific side from Hachinohe Port in Aomori Prefecture to Kashima Port in Ibaraki Prefecture were damaged. Several damages such as settlement of structure and large faulting between the quay were seen in the damaged port. But fishing ports and harbors contributed greatly to recovery after the earthquake because the port function was quickly restored. The probability of the Nankai Trough Earthquake to occur within the next 30 years is estimated to be between seventy and eighty percent. When the Nankai Trough Earthquake occurs, there is a risk of damage to a wide area from Kyushu region to Tokai region. After the earthquake, Kochi prefecture may have difficulty receiving help such as transportation of supplies from the land route as it is surrounded by steep mountains. There are 88 fishing ports in Kochi Prefecture, part of the fishing port is considered to be at the time of the earthquake will be used as disaster prevention centers as well as the Tohoku region Pacific Ocean earthquake. Currently, seismic reinforcement and maintenance of several fishing ports, which are disaster prevention bases, are forwarding.
ABSTRACT This paper described the reinforced breakwater foundation against earthquake and tsunami induced failure. To resist the compound disaster of earthquake and tsunami, the breakwater model used steel sheet pile, gabion, impervious filling material and tetrapod to make the foundation of breakwater resilient. In order to evaluate the effectiveness of proposed breakwater models, a series of shaking table tests and tsunami overflow tests were performed on the breakwater. And the results showed that the improved breakwater foundation effectively reduced the damage from the earthquake and tsunami. INTRODUCTION The 2004 Indian Ocean Earthquake, the 2011 Off the Pacific Coast of Tohoku Earthquake and the tsunamis induced caused catastrophic losses to lives and living environments. The 2004 Indian Ocean tsunami which was one of the deadliest tsunamis resulting about 292,000 deaths. And the 2011 Off the Pacific Coast of Tohoku Earthquake and tsunami caused an economic loss of US$235 billion which was registered to be the costliest natural disaster in the world history according to the report of World Bank. The 2011 Off the Pacific Coast of Tohoku Earthquake was the most powerful earthquake ever recorded in Japan which induced a tsunami that destroyed lots of buildings and structures along the coast of Tohoku region. Many coastal structures were damaged by the compound disasters such as breakwaters, sea walls, coastal dikes and so on (Hara et al. 2012; Hazarika et al. 2012, 2013; Takahashi et al. 2011). The Kamaishi port breakwater (Iwate Prefecture, Japan), recognized as the world’s deepest (63 m) breakwater, was one of the breakwaters destroyed by the disaster. The caissons of the breakwater displaced, tilted or settled. The main reason of the failure was the damage of breakwater mound which caused the sliding or collapsing of caissons. The Japanese government, Ministry of Land, Infrastructure, Transport and Tourism (MLIT) analysed the reasons of breakwaters' failure in the 2011 Off the Pacific Coast of Tohoku Earthquake and Tsunami (MLIT, 2011; MLIT, 2013): (1) Huge horizontal tsunami forces acting on the breakwater due to the large water level difference between two sides of breakwater; (2) The mound and foundation soils scoured by overflowed tsunami flows; (3) Seepage flow in the foundation increased much due to the large water level difference between two sides of the breakwater. Among the damaged breakwaters in the disaster, many of them (Hachinohe Port Breakwater, Aomori Prefecture; Soma Port Breakwater, Fukushima Prefecture; Kuji Port Breakwater, Iwate Prefecture) failed due to the damage of mound during the earthquake and tsunami. The damage of mound affected the stability of caisson more than the tsunami wave. Therefore, improving the mound and foundation is very important to keep the breakwater stable against the earthquake and tsunami.
ABSTRACT This thesis investigates the collision force of driftwoods and small boats due to tsunamis. Even though there are some calculation formulas from past experiments, quantitative approaches for design criteria of tsunami protection structures are not established. Accordingly, to upgrade design criteria of tsunami protection structures, the thesis aimed to investigate into an adaptability of the formulas obtained past researches and new experimental evaluation formula derived from present research comparing with the measurements of hydraulic model experiment. INTRODUCTION On March 11, 2011, Tohoku - Pacific Coast Earthquake tsunami struck a large area on the Pacific coast, especially from Chiba Prefecture to the coastal areas of Aomori Prefecture, where the damage to coastal structures was so great, not only port facilities, but also shore protection facilities such as breakwater, seawall, and sea embankment. In particular, the area around the Fukushima Daiichi nuclear power plant suffered from the damage generated by radiation leak due to tsunamis. On the other hand, it was confirmed that the Kamaishi bay-mouth breakwater delayed reaching tsunami in the bay and had the effect of reducing the tsunami height. In the shore protective facilities such as breakwater, it is considered to have protective effect on the tsunami(Hiraishi et al., 2011). Accordingly, it is necessary to make the shore protective facilities tenacious structure that can withstand the port structure without collapsing even for the largest scale tsunami. In this way, this report investigates the collision force of driftwoods and small boats due to tsunamis. Even though there are some calculation formulas from previous researches, quantitative approaches for design criteria of tsunami protection structures are not established. Accordingly, to upgrade design criteria of tsunami protection structures, the research aimed to investigate into an adaptability of the formulas from previous researches and new experimental evaluation formula derived from present research. In this paper, to compare the measurements with the calculation formula, we have a hydraulic model experiment. With regard to small boat, we use the measurements of experiment conducted in 2017 and of similar experiments conducted in 2016(Okura, 2017) and 2015(Ono and Hiraishi, 2017) as well in this experiment. In contrast, with regard to driftwood, we use the measurements of similar experiments conducted in 2016 and 2015.
Kim, Chol-Ho (Department of Engineering, Hokoku Engineering Co., Ltd) | Fujii, Mamoru (Department of Architecture and Building Engineering, Tokai University) | Shinagawa, Kyoichi (Institute of Soil Exploration and Investigations, Lasting Co., Ltd) | Ogawa, Masahiro (Department of Engineering, Hokoku Engineering Co., Ltd)
ABSTRACT: The east Japan great earthquake struck from the northeast of Japan to the whole area of Kanto with a magnitude of 9.0 and maximum seismic intensity of 7 on March 11, 2011. Seismic hazard such as liquefaction has especially affected a number of detached houses. From the results of in-situ investigation, the authors found that the liquefaction damage is apparently concentrated on newly reclaimed land, and closely related to the thickness of weak soil, soil types and groundwater level. In addition, where ground improvement method had been already carried out, damage to buildings, facilities and detached houses located even in the newly reclaimed land were found to be very small. In order to predict and prepare for liquefaction, information of the soil classification and groundwater level as well as soil strength and density are important parameters, and these kinds of information also become necessary for considering the rational countermeasures to liquefaction. INTRODUCTION The east Japan great earthquake struck from the northeast Japan to the whole area of Kanto with a magnitude of 9.0 and maximum seismic intensity of 7 (Kurihara city, Miyagi Prefecture) on March 11, 2011. Seismic hazards such as tsunami and liquefaction have especially affected detached houses. At present, in spite of announcement #1113 of the Ministry of Land, Infrastructure, Transportation and Tourism which addresses the possibilities of liquefaction, organized/systematic measure of liquefaction has hardly been accomplished for detached houses. The authors investigated the damage caused by liquefaction in the Urayasu area, Chiba Prefecture, where severe liquefaction damage has occurred. OUTLINE OF THE EARTHQUAKE DAMAGE IN URAYASU AREA Extensive damage has occurred in northeast Japan by the east Japan great earthquake, from Aomori to Kanagawa prefectures, especially where the seismic intensity of more than 5+ was observed.
Komai, Takeshi (Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan) | Kawabe, Yoshishige (Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan) | Hara, Junko (Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan) | Sakamoto, Yasuhide (Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan) | Zhang, Ming (Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan)
ABSTRACT: We have surveyed tsunami flooding areas from Aomori to Chiba prefecture to identify various kinds of geological and geochemical evidences occurred by Tsunami disaster. As a result, it was found that tsunami sediments have layering structure of several hits in a couple of hours. The lands are covered by almost sandy sediments with some layers of silt and mud or clay minerals, which have relatively higher content of organic substances and sulfur. Soils and sediments originated from tsunami contain relatively higher concentration of arsenic and lead elements, compared with natural background. This suggests that the sediments were transported from offshore marine mud with anaerobic environment. In some cases, risk mitigation will be necessary for safe land utilization. INTRODUCTION The earthquake on March 11, 2011 at coastal areas of northeastern Japan caused a lot of catastrophic damages of tsunami, flooding and liquefaction of land, and earthquake itself. Particularly terrible scale of Tsunami waves hit coastal area with deformation and flooding of land. A large amount of tsunami sediments and the resulting debris remained at Tsunami suffered areas, which are still barrier from the reconstruction. However, if the sediments and soils are not contaminated, they will be able to utilize for agriculture and civil engineering activities. Urgent investigation during Mar. to Sep, 2011 was performed to investigate tsunami flooding areas from Aomori to Chiba prefecture and to identify various kinds of geological and geochemical evidences occurred by large Tsunami hits. As a result, it was found that Tsunami sediments have a layering structure of several hits in a couple of hours. This suggests that the sediments including toxic elements were transported from offshore marine mud with anaerobic environment. We continue to work for more detailed survey and analysis on the characteristics of tsunami sediments and soil contamination.
ABSTRACT ABSTRACT: Soft sedimentary rocks have a characteristic behavior, dilatancy. Changes of stress conditions may cause shearing with volume expansion/compression. When a rock sample is compressed, its volume is subsequently changed, resulting that the flow-paths might be also evolved. Thus, permeability within a domain is influenced by volumetric strain mediated by alternation of stress conditions. This alternation of permeability may exert influence over stress conditions because the water pressure may change under an undrained condition. Therefore, this linked alternation processes among stress conditions, volumetric strain, and permeability, should be considered. This paper is aimed to examine the coupled mechanical and hydraulic behavior by conducting triaxial compressive and flow-through experiments using pumice tuff, and then a relation between volumetric strain and permeability is proposed. After the experiments are terminated, X-ray CT analysis is conducted to examine in-sample microscopic structures, focusing on fractures induced by the compression and flow tests. 1. INTRODUCTION Effective uses for underground spaces have been of significant importance in recent years. A radioactive waste repository has been investigated for a practical use. Especially, in Japan relatively high low-level radioactive wastes are planned to be disposed below the generally used depth; 50 to 100 m, and the research works on soft sedimentary rocks have been studied . Tomita et al. have studied about rock-fall and induced cracks at a test cavern for low-level radioactive waste in soft rock at Rokkasyo village in Aomori Prefecture. This study proposes a failure criterion by element experiments simulating stress paths during excavation. Then, excavation disturbed zones surrounding the cavern is examined by the numerical analysis with the failure criterion. Soft rock is defined as the material that presents dynamic behavior in the middle of soils and rocks. It is commonly known that the mechanical behaviors of soft sedimentary rock are elastoplastic, dilatants, strain hardening-strain softening at lower confining stress level, and time dependent. Especially, it is necessary to be carefully taken into account that the characteristic of dilatancy may lead to a change of pore structures and of induced permeability. Thus, it is important to describe the interaction of the mechanical and hydraulic behavior. However, the research works that evaluates this relation are sparse. Lu.P has proposed an empirical relation between a pore-volumetric strain and permeability in clayey siltstone  and L.D.Yang et al. improved the relation and also extended to apply this to brown mudstone . The aim of this paper is to investigate the permeability of pumice tuff influenced by dilatancy under several stress conditions, by conducting the coupled triaxial shear-flow experiments. Moreover, X-ray fluorescence analysis and X-ray computed tomography are also performed to examine the mineral composition of pumice tuff and the microstructure using the pre- and post-experiment samples, respectively. 2. TRIAXIAL SHEAR-FLOW TEST 2.1. Specimens Cylindrical specimens used for the this work are cored from bulk blocks of pumice tuff with dimensions of the height of 100mm and diameter of 50mm. The five samples from No.1 to 5, are shaped - No.1 is used for X-ray CT analysis as a representative under preexperimental conditions, No.3 is used for shear test, No.4 and No.5 are used for shear-flow tests and X-ray fluorescence analysis (Table 1).
ABSTRACT: The aim of this paper is to study spalling in soft rock excavation. The large test cavern in soft rock was excavated to investigate the Excavation Disturbed Zone (EDZ) of the radioactive waste disposal project in Japan. During the excavation, the rock-fall and the induced crack, which was the low dip angle near the cavern surface caused by spalling, occurred. These spalling are similar to the failure for the stress concentration due to the excavation of the hard rock at the deep underground. The competence factor of the rock, which is the ratio of rock strength to in situ stress, is smaller than two, which means the strength of the rock is low relative to the in situ stress, and this site corresponds to the rock mass with relatively high rock stress. Therefore, we have carried out the stress paths simulation test, which are the triaxial compression tests in consideration of stress path, which assumed the change in the stress around the cavern during the underground openings. As a result, the splitting failure has been confirmed under low confining stress, which range is less than 0.4 MPa. On the other hand, in the confining stress range of more than 0.4 MPa, the shear failure has confirmed. The induced stress around the cavern decreases due to the underground openings. Therefore, it is thought that the crack confirmed in the test cavern is the splitting failure under stress decrease. Furthermore, the failure zone surrounding the cavern was proved by the numerical analysis applying the failure criterion based on the results of the above-mentioned triaxial test. INTRODUCTION Japan Nuclear Fuel Limited (JNFL) has a plan of a new facility for Low-Level Radioactive Waste (LLW) of underground disposal with the engineered barrier. This facility can accept the relatively higher LLW from nuclear power plant operations and in core materials from the reactor decommissioning. JNFL site is located in the legislated development area in Rokkasho-mura, Aomori Prefecture in the northern part of mainland Japan, which is about 700 km away from Tokyo. The detailed investigation of geology and ground water has been carried out since 2002 in order to collect various data for the safety review. As a part of the investigation, the tunnel and the test cavern have been excavated to acquire the knowledge on mechanical stability of openings and the excavation disturbed zone (EDZ), which is shown in Figure 1. Fig. 1. available in full paper. The excavation of the 1 km long approach tunnel (the portal level EL. 8.0 m, incline of 1/10) to the altitude of EL. -86.0 m underground has been finished in 2004. Moreover, the large-scale test cavern has been completed in June 2005. Prior to the test cavern excavation, the three measurement tunnels had been excavated within a 20 m vicinity of the test cavern and the measuring instruments had been installed in order to examine the rock behavior.
ABSTRACT Great advance has been achieved in JAMSTEC since the last IDOT meeting in 1996. (1) Long term and realtime deep seafloor observatories were deployed at four sites around Japan. (2) Operation of the full ocean depth ROV Kaiko is getting very wall and expanding. In March 2000, the new 3000-meter ROV Hyper- Dolphin joined the JAMSTEC fleet. She is equipped with an ultralow light level Hi-Vision (Super-HAAP Hi-Vision) camera. (3) The prototype bore hole reentry system was completed in 2000. Tether cable is shared with that of the Kaiko on board the R/V Kairei. (4) Deep and long range AUV Urashima was launched in March 2000. Maximum depth capability is 3500 m, and maximum duration is 300 km at a cruising speed of 3 knots, which is powered by fuel cell. (5) Japanese deep sea drilling project OD 21 started in 2000. The 57500 G/T drilling vessel will be completed in 2004. Maximum drilling capability using a riser system will be 7000 m under the seafloor at maximum operating water depth of 4000 m. INTRODUCTION In January 2001, the Japanese government was streamlined from 22 ministries and agencies into 12. The Science & Technology Agency (STA), from which the JAMSTEC had been funded, and the Ministry of Education was merged into the Ministry of Science and Education. With this rearrangement, role of the JAMSTEC has been increasing more than ever. Since its foundation in 1971, the JAMSTEC is celebrating 30th anniversary in the year of 2001. The JAMSTEC has seven offices and branches, including headquarters in Yokosuka, branches in Tokyo, Yokohama, Mutsu in Aomori Prefecture, Hawaii, Alaska and Washington D.C.. In the early 2001, new branches opened in Okinawa and Seattle. The annual budget in the Fiscal Year 2000 (between April 2000 and March 2001) was approximately 500 million USD.
Kim, June-Q (Toyo Construction Co.) | Iwata, Koichiro (Nagoya University) | Mizutani, Norimi (Nagoya University) | Suzuki, Atsushi (Nagoya University) | Ruffin, Teofilo Monge (United Nations Center for Regional Development)
ABSTRACT An experiment on cubical submerged structure like artificial fish reef is conducted to determine the flow field and mechanisms of local scouring and resultant embedment. Moreover, a numerical scheme for three-dimensional flow field computation including- the vortex formations is developed. Based on the results, the pertinent characteristics of flow field arc discussed in relation to the vortex 1bnnations. For movable bed, the vortex formation and the steady outward flows from the structure are very significant in local scouring which is directly responsible in the embedment of the structure. The relationships between the flow field due to variation of KC and Re numbers with the maximum values of scouring depth and embedment are discussed. Lastly, the flow patterns and vortex formation are well evaluated by the numerical computation; thus, the characteristics of the computed flow field explain well file generation mechanisms of local sourcing. INTRODUCTION Artificial fish reefs are today a well established fishery enchancement technique that is being- practiced around the world. For the past centuries, marine anglers have used artificial fish reefs to enhance their fishing efforts by placing rocks in bottom bed. Historical records show that the placement of rocks to enhance kelp production has been the common practice of Japanese fishermen since the late seventeenth century (Aomori Prefecture. 1980). However, during storms and high waves, most of these rocks are moved of severely embedded: thus, many of the attached organisms are crushed and the sheltering of other living organisms in the zone of enhancement is greatly disturbed. Because of the poor stability and very low durability" of-these kinds of fishing reefs, it is more economical and efficient in the long run to build artificial reels with specially designed structures and durable materials.