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1.
破碎区至冲泻区水动力特性分析是研究近岸地区泥沙输运机理和岸滩演变的关键。考虑潜堤修建的影响,对破碎区至冲泻区水动力特性开展研究。运用基于RANS方程的波浪数学模型,选取非线性涡粘性κ-ε紊动传输模型,采用高精度PLIC-VOF方法追踪自由面,并用实验数据验证模型精度。计算分析结果表明,潜堤的修建改变了破波点的位置,破碎区至冲泻区内水动力特性随之变化,入射波波高H、波长L、堤顶水深R和堤顶宽度B是主要影响因素。在相同的入射波条件下,B/R增大,破碎区至冲泻区内出现的最大紊动动能值和最大紊动耗散值减小。用量纲一参数Re,Fr和St来描述破碎区至冲泻区水动力特性,随着RL/BH增大,波浪将在离岸较近处发生破碎,Re和Fr增大,St减小。 相似文献
2.
Following the catastrophic “Great Sumatra–Andaman” earthquake- tsunami in the Indian Ocean on the 26th December 2004, questions
have been asked about the frequency and magnitude of tsunami within the region. We present a summary of the previously published
lists of Indian Ocean Tsunami (IOT) and the results of a preliminary search of archival materials held at the India Records
Office, at the British Library in London. We demonstrate that in some cases, normal tidal movements and floods associated
with tropical cyclones have been erroneously listed as tsunami. We summarise archival material for tsunami that occurred in
1945, 1941, 1881, 1819, 1762 and a little known tsunami in 1843. We present the results of modelling of the 2004, 1861 and
1833 tsunami generated by earthquakes off Sumatra and the 1945 Makran earthquake and tsunami, and examine how these results
help to explain some of the historical observations. The highly directional component to tsunami propagation illustrated by
the numerical models may explain why we are unable to locate archival records of the 1861 and 1833 tsunami at important locations
like Rangoon, Kolkata (formally Calcutta) and Chennai (formally Madras), despite reports that these events created large tsunami
that inundated western Sumatra. The numerical models identify other areas (particularly the central and southern Indian Ocean
islands) where the 1833 tsunami may have had a large enough effect to produce a historic record. We recommend further archival
research, coastal geological investigations of tsunami impacts and detailed modelling of tsunami propagation to better understand
the record and effects of tsunami in the Indian Ocean and to estimate their likelihood of occurring in the future. 相似文献
3.
Babloo Chaudhary Hemanta Hazarika Akira Murakami Kazunori Fujisawa 《Acta Geotechnica》2018,13(4):997-1017
Many breakwaters have collapsed in the past due to earthquakes and subsequent tsunamis, resulting in considerable devastation as the breakwaters failed to prevent the tsunami from entering the coastal plain areas. Breakwater failures are mainly caused by damage to its foundation ground. However, the damage mechanism of breakwater foundation during earthquakes and tsunamis remains unclear. This study focuses on the breakwater failure mechanism due to collapse of its foundation under the action of an earthquake and subsequent tsunami. In addition, reinforcing countermeasures for breakwater foundation to mitigate damage due to compound geodisasters triggered by earthquakes and tsunamis are proposed. Sheet piles and gabions were used in the breakwater foundation as reinforcing countermeasures. To evaluate the effectiveness of the reinforced foundation, a series of shaking table tests and hydraulic model tests were performed. The tsunami overflow tests were conducted on the same model after the earthquake loadings, and comparisons were made between the conventional and reinforced foundations. It was observed during the tests that the reinforced foundation could effectively reduce the damage to the breakwater caused by earthquake and tsunami-induced forces. Numerical analyses were performed to clarify the mechanism of the soil–breakwater–reinforcement–fluid system. Overall, this study is useful in practical engineering, and the reinforcing foundation model could be adopted for offshore structures to reduce damage from earthquakes and tsunamis in the future. 相似文献
4.
Flood risk curves and uncertainty bounds 总被引：7，自引：5，他引：2
The Scotia Arc is one of two regions in the Atlantic Ocean with greater potential for tsunami generation from seismic and
volcanic sources. A numerical modeling study was undertaken to determine tsunami generation from postulated sources along
the Arc and tsunami wave amplification or attenuation along the Patagonian continental shelf. Sea level oscillation represented
by a simple sinusoidal wave function applied at the boundary of the numerical grid, which simulated the tsunami entering the
computational domain, was implemented as forcing. The validation of this model was carried out by comparing the maximum amplitudes
recorded and simulated at Santa Teresita and Mar del Plata (Buenos Aires province) after the occurrence of earthquake and
subsequent tsunami in Sumatra (December 2004). From numerical simulations it can be seen that the tsunami propagation is highly
affected by bathymetric refraction on the Patagonian continental shelf and the wave amplitude is significantly attenuated
on the inner continental shelf. Maximum amplifications were obtained around Malvinas (Falkland) Islands and Burdwood bank
because the wave propagates almost without refracting and the shoaling effect is highly significant there. 相似文献
5.
Atsushi Noda Hajime Katayama Tsumoru Sagayama Kazuya Suga Yasuhito Uchida Kenji Satake Kohei Abe Yukinobu Okamura 《Sedimentary Geology》2007,200(3-4):314-327
A combined approach of field geology and numerical simulation was conducted for evaluating the tsunami impacts on the shelf sediments. The 2003 Tokachi-oki earthquake, M 8.0, that occurred on 25 September 2003 off southeastern Hokkaido, northern Japan, generated a locally destructive tsunami. Maximum run-up height of the tsunami waves reached 4 m above sea level. In order to estimate the tsunami impacts on shallow marine sediments, we compared pre- and post-tsunami marine sediments in water depths of 38–112 m in terms of grain size, sedimentary structure, and microfossil content. Decreases of fine fractions, especially finer than very fine sand, which led to coarsen the mean grain size, were detected in the inner shelf of the northern part of the study area. Foraminiferal assemblages also changed in the coarsened sediments. On the other hand, the other shelf sediments largely unchanged or slightly fined. We also simulated the tsunami wave velocity and direction, and grain size entrained by the modeled tsunami. The numerical simulation resulted in that the 2003 tsunami could transport very fine sand in water depths shallower than 45–95 m at the northern part of the study area. This is comparable with the actual grain-size changes after the tsunami had passed. However, some storms and tidal currents might also be possible to stir the surface sediments after the pre-tsunami survey, so we could not conclude that the grain-size changes had been caused only by the tsunami. Nevertheless, a combined approach of sampling and modeling was powerful for estimating the tsunami impacts under the sea. 相似文献
6.
7.
Shunichi Koshimura Toshitaka Katada Harold O. Mofjeld Yoshiaki Kawata 《Natural Hazards》2006,39(2):265-274
This study develops a method for estimating the number of casualties that may occur while people evacuate from an inundation
zone when a tsunami has inundated an area. The method is based on a simple model of hydrodynamic forces as they affect the
human body. The method uses a Tsunami casualty index (TCI) computed at each grid point of a numerical tsunami model to determine
locations and times within the tsunami inundation zone where evacuation during the tsunami inundation is not possible and
therefore where casualties are likely to occur. The locations and times can be combined with information about population
density to compute the potential number of casualties. This information is useful in developing tsunami evacuation routes
that avoid such locations. To illustrate the method, it is applied to the Seattle waterfront in Washington State, USA, that
is under the threat of possible tsunami disasters due to Seattle Fault earthquakes. Preliminary results suggest that the tsunami
casualties may occur within the Seattle waterfront for 15 min, during the time interval from 3 to 18 min after a large Seattle
Fault tsunami is generated when the background tide level is mean high water. 相似文献
8.
Turkey was struck by two major events on 17 August and 12 November 1999, named Izmit (M w = 7.4) and Düzce (M w = 7.2) earthquakes, respectively. Rubble mound breakwaters in Izmit Bay experienced little damage, as forecasted by the new risk assessment model in which tsunami occurrence risk was included in the damage estimations. In order to determine the occurrence probability of structural damage under design conditions, including the environmental loading parameters of tsunami and storm waves, tidal range and storm surge, the Conditional Expections Monte Carlo simulation was applied in the risk assessment model developed in this study for the Esenköy Fishery Harbour, Turkey. A tsunami was not the key design parameter when compared to storm waves for the main breakwater of the harbour, however, in places with great seismic activity, the tsunami risk should be important depending on the occurrence probability and magnitude of the tsunami. 相似文献
9.
Assessing the threat to Western Australia from tsunami generated by earthquakes along the Sunda Arc 总被引：1，自引：1，他引：1
A suite of tsunami spaced evenly along the subduction zone to the south of Indonesia (the Sunda Arc) were numerically modelled
in order to make a preliminary estimate of the level of threat faced by Western Australia from tsunami generated along the
Arc. Offshore wave heights from these tsunami were predicted to be significantly higher along the northern part of the west
Australian coast than for the rest of the coast south of the town of Exmouth. In particular, the area around Exmouth may face
a higher tsunami hazard than other areas of the West Australian coast nearby. Large earthquakes offshore of Java and Sumbawa
are likely to be a greater hazard to WA than those offshore of Sumatra. Our numerical models indicate that a magnitude 9 or
above earthquake along the eastern part of the Sunda Arc has the potential to significantly impact a large part of the West
Australian coastline.
The Australian government reserves the right to retain a non-exclusive, royalty free license in and to any copyright. 相似文献
10.
Monte Kietpawpan Parichart Visuthismajarn Charlchai Tanavud Mark G. Robson 《Natural Hazards》2008,46(1):89-106
A new model to calculate tsunami travel times in the Andaman Sea region has been developed. The model specifically provides
more accurate travel time estimates for tsunamis propagating to Patong Beach on the west coast of Phuket, Thailand. More generally,
the model provides better understanding of the influence of the accuracy and resolution of bathymetry data on the accuracy
of travel time calculations. The dynamic model is based on solitary wave theory, and a lookup function is used to perform
bilinear interpolation of bathymetry along the ray trajectory. The model was calibrated and verified using data from an echosounder
record, tsunami photographs, satellite altimetry records, and eyewitness accounts of the tsunami on 26 December 2004. Time
differences for 12 representative targets in the Andaman Sea and the Indian Ocean regions were calculated. The model demonstrated
satisfactory time differences (<2 min/h), despite the use of low resolution bathymetry (ETOPO2v2). To improve accuracy, the
dynamics of wave elevation and a velocity correction term must be considered, particularly for calculations in the nearshore
region. 相似文献