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1.
Shear wave velocity-based liquefaction evaluation in the great Wenchuan earthquake： a preliminary case study 总被引：2，自引：1，他引：1
The great Wenchuan earthquake (Ms = 8.0) in 2008 caused severe damage in the western part of the Chengdu Plain. Soil liquefaction was one of the major causes of damage in the plain areas, and proper evaluation of liquefaction potential is important in the definition of the seismic hazard facing a given region and post-earthquake reconstruction. In this paper, a simplified procedure is proposed for liquefaction assessment of sandy deposits using shear wave velocity (Vs), and soil liquefaction from the Banqiao School site was preliminarily investigated after the earthquake. Boreholes were made at the site and shear wave velocities were measured both by SASW and down-hole methods. Based on the in-situ soil information and Vs profiles, the liquefaction potential of this site was evaluated. The results are reasonably consistent with the actual field behavior observed after the earthquake, indicating that the proposed procedure is effective. The possible effects of gravel and fines contents on liquefaction of sandy soils were also briefly discussed. 相似文献
2.
传统二维震害图像方法对震后区域进行研究时,由于其拍摄角度具有局限性,震后区域图像的视觉效果不理想。提出基于三维激光扫描技术的震后区域三维虚拟重建方法,采用三维激光扫描仪测量震后区域,获取该区域的点云数据,采用Cyclone软件合并点云数据后,得到震后区域拼接后的整体点云图,将该图点云数据进行去体外孤点、去噪声点以及点云取样等处理后实施封装,在封装的点云数据上采用Sketch模型实施贴图操作,实现视觉传达效果理想的震后区域三维图形的虚拟重建。实验证明,所提方法对震后区域的三维图像虚拟重建结果精度高、视觉效果好。 相似文献
3.
XU Chong TIAN Ying-ying SHEN Ling-ling MA Si-yuan XU Xi-wei ZHOU Ben-gang HUANG Xue-qiang MA Jun-xue CHEN Xi 《地震地质》2018,40(5):1115-1128
In this study, a detailed database of landslides triggered by the 25 April 2015 Gorkha (Nepal)MW7.8 earthquake is constructed based on visual interpretation of pre- and post-earthquake high-resolution satellite images and field reconnaissance. Results show the earthquake triggered at least 47 200 landslides, which have a NWW direction spatial distribution, similar with the location and strike of the seismogenic fault. The landslides are of a total area about 110km2 and an oval distribution area about 35 700km2. On the basis of a scale relationship between landslide area (A)and volume (V), V=1.314 7×A1.208 5, the total volume of the coseismic landslides is estimated to be about 9.64×108m3. In the oval landslide distribution area, the landslide number density, area density, and volume density were calculated and the results are 1.32km-2, 0.31%, and 0.027m, respectively. This study provides a detailed and objective inventory of landslides triggered by the Gorkha earthquake, which provides very important and essential basic data for study of mechanics of coseismic landslides, spatial pattern, distribution law, and hazard assessment. In addition, the landslide database related to an individual earthquake also provides an important earthquake case in a subduction zone for studying landslides related to multiple earthquakes from a global perspective. 相似文献
4.
As urban systems become more highly sophisticated and interdependent, their vulnerability to earthquake events exhibits a significant level of uncertainties. Thus, community-level seismic risk assessments are indispensable to facilitate decision making for effective hazard mitigation and disaster responses. To this end, new frameworks for pre- and post-earthquake regional loss assessments are proposed using deep learning methods. First, to improve the accuracy of the response prediction of individual structures during the pre-earthquake loss assessment, a widely used nonlinear static procedure is replaced by the recently developed probabilistic deep neural network model. The variabilities of the nonlinear responses of a structural system given the seismic intensity can be quantified during the loss assessment process. Second, to facilitate near-real-time post-earthquake loss assessments, an adaptive algorithm, which identifies the optimal number and locations of sensors in a given urban area, is proposed. Using a deep neural network that estimates area-wide structural damage given the spatial distribution of the seismic intensity levels as a surrogate model, the algorithm adaptively places additional sensors at property lots at which errors from surrogate estimations of the structural damage are the greatest. Note that the surrogate model is constructed before earthquake events using simulated datasets. To test and demonstrate the proposed frameworks, the paper introduces thorough numerical investigations of two hypothetical urban communities. The proposed frameworks using the deep learning methods are expected to make critical advances in pre- and post-earthquake regional loss assessments. 相似文献
5.
The M w = 7.2 Haiti earthquake of 12th January 2010 caused extensive damage to buildings and other infrastructure in the epicentral region in and around Port-au-Prince. The Earthquake Engineering Field Investigation Team (EEFIT), which is based in the United Kingdom, organised a field mission to Haiti with the authors as the team members. The paper presents the geotechnical findings of the team including those relating to soil liquefaction and lateral spreading and discusses the performance of buildings, including historic buildings, and bridges. Unprecedented use was made of damage assessments made from remote images (i.e. images taken from satellites and aircraft) when planning the post-earthquake relief effort in Haiti and a principal objective of the team was to evaluate the accuracy of such assessments. Accordingly, 142 buildings in Port-au-Prince were inspected in the field by the EEFIT team; damage assessments had previously been made using remote images for all these buildings. On the basis of this survey, the tendency of remote assessments to underestimate damage was confirmed; it was found that the underestimate applied to assessments based on oblique images using the relatively new technique of Pictometry, as well as those based on vertical images, although to a lesser degree. The paper also discusses the distribution of damage in Port-au-Prince, which was found to be strongly clustered in ways that appear not to have been completely explained. 相似文献
6.
2017年8月8日九寨沟7.0级地震引发贯通重灾区的S301省道、Z120县道多处损坏,给应急救援和灾后重建带来较大困难。利用高分辨率无人机和卫星影像可以对道路震害情况进行评估。本文首先对道路震害进行破坏类型和破坏等级的划分,针对不同分辨率影像所表现的道路破坏特征,建立各破坏等级、各损坏类型的解译标志,并完成灾区遥感图像覆盖范围内主要道路震害的研判与评估。经统计分析,研究区域共出现110处明显破坏,其中,68处为部分损坏,42处为完全损毁,道路整体破坏严重。 相似文献
7.
针对中分辨率遥感影像建筑物震害信息弱以及变化检测法受非震害信息影响大等弱点, 本文建立了一种基于变化检测的居民区震害信息快速提取方法. 该方法利用主成分变换增强震害信息, 采用监督分类法提取似居民区, 并用灯光影像数据进一步对似居民区提取结果进行优化, 从而很好地消除了变化检测方法中非震害因素的影响. 在此基础上, 以2001年印度MW7.6地震的极重灾区为研究区域, 利用震前、 震后Landsat卫星TM图像和震区灯光影像数据, 对本文算法进行了验证和分析. 结果表明, 在30—50 m中分辨率遥感影像上, 以建筑物为主的居民区震后图像变化最为显著的震害特征是反射率变大, 本文所建立的居民区震害信息提取方法在解决中分辨率遥感影像震害目标信息弱、 背景复杂等方面效果明显. 相似文献
8.
近岸水平场地液化侧向大变形机理及软化模量分析方法 总被引：3，自引：1，他引：3
本文依据震害现象和实验探讨近岸水平场地地面液化侧向大变形机理，改进现有软化模量分析技术，给出一套地面液化侧向大变形的分析方法。近岸水平场地侧向大变形机理因地基中孔隙水压力升高、土体模量衰减、土骨架变软使偏应变得到充分发展所致，其水平永久侧移可用从底部到顶部呈增加形式的整体变形描述。利用本文方法，对1995年阪神地震中近岸沉箱岸壁和土体液化侧向大变形进行了数值模拟，结果与震后实测结果和试验结果在主要特征上一致，说明改进的软化模量法可以用于地面液化侧向大变形的分析。 相似文献
9.
高分遥感影像震害提取的变化检测算法改进 总被引：1，自引：0，他引：1
本文针对遥感多时相变化检测应用于地震灾害信息提取中存在的问题, 提出一种改进算法, 通过搜索震后影像上建筑物在震前影像上对应区域周边一定范围内的影像相关性最大值(区域寻优)来代替传统上严格对应像元的相关系数值, 以减少因配准精度、 摄影方位、 地表高程、 建筑物高度等造成的同名地物变形对变化检测结果的影响, 提高基于相关系数变化检测的精度。 以都江堰市城区在2008年汶川地震震前的QuickBird影像和震后的航空遥感影像为实验对象, 采用本文方法进行了震害变化检测实验, 并与传统方法进行了比较, 表明改进的算法能够提高震害信息提取的精度且具有一定的稳定性。 相似文献
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11.
基于多源卫星数据的小型水体蓝藻水华联合监测——以天津于桥水库为例 总被引：3，自引：0，他引：3
近年来水体富营养化呈扩张趋势,蓝藻水华不仅在太湖等大型湖泊频发,水面面积较小的天津于桥水库等也形势严峻,亟需加强卫星遥感监测.但是,以往在太湖等业务化使用非常成功的MODIS等卫星数据(约500 m),由于空间分辨率较低,难以满足小型水体的监测要求;而Landsat-8等空间分辨率较高的卫星数据(30 m),通常重返周期较长,无法满足水华高频监测需求.本文以天津市于桥水库(面积约80 km2)为研究区,针对常用的卫星数据,从空间、时间、光谱范围和数据可获取性共4个方面,评价不同卫星数据蓝藻水华监测能力和算法,同时对不同卫星监测结果一致性进行评估.结果表明:(1)筛选出国产HJ-1A\B CCD、GF-1 WFV和美国Landsat-8 OLI这3种卫星波段合适,空间分辨率较高,适用于桥水库蓝藻水华监测,但考虑到其重返周期较长,建议多星联合观测;(2)各个卫星监测结果与卫星影像目视解译结果基本一致,均方根误差和相对误差均分别控制在0.78 km2和4.9%以内;(3)不同卫星监测结果一致性良好,一致性精度达到99.5%;(4)根据历史影像结果,发现于桥水库2016年水质开始呈富营养化,藻华现象在夏、秋两季最为严重.研究表明,针对小型水面水体蓝藻水华监测,利用较高分辨率数据联合监测,是一种有效的替代策略,今后可在更多小型水域推广. 相似文献
12.
《Marine pollution bulletin》2014,78(1-2):190-195
Increased frequency and enhanced damage to the marine environment and to human society caused by green macroalgae blooms demand improved high-resolution early detection methods. Conventional satellite remote sensing methods via spectra radiometers do not work in cloud-covered areas, and therefore cannot meet these demands for operational applications. We present a methodology for green macroalgae bloom detection based on RADARSAT-2 synthetic aperture radar (SAR) images. Green macroalgae patches exhibit different polarimetric characteristics compared to the open ocean surface, in both the amplitude and phase domains of SAR-measured complex radar backscatter returns. In this study, new index factors are defined which have opposite signs in green macroalgae-covered areas, compared to the open water surface. These index factors enable unsupervised detection from SAR images, providing a high-resolution new tool for detection of green macroalgae blooms, which can potentially contribute to a better understanding of the mechanisms related to outbreaks of green macroalgae blooms in coastal areas throughout the world ocean. 相似文献
13.
Mapping the mesoscale surface velocity stream function by combining estimates of surface height from satellite altimetry
and surface currents from sequential infrared (sea-surface temperature) imagery using optimal interpolation is described.
Surface currents are computed from infrared images by the method of maximum cross-correlations (MCC) and are combined with
altimeter sea-level anomaly data from the TOPEX/Poseidon and ERS satellites. The analysis method was applied to 6 years of
data from the East Australian Current region. The covariance of velocity and sea-level data is consistent with the statistical
assumptions of homogeneous, isotropic turbulence, with typical length scales of order 220 km and time scales of 10 days in
this region. Augmenting the analysis of altimeter data with MCC velocity observations improves the resolution of the surface
currents, especially near the Australian coast, and demonstrates that the two data sources provide consistent and complementary
observations of the surface mesoscale circulation. The volume of MCC data is comparable to that from a satellite altimeter,
but with a more variable distribution of spatial and temporal resolution. In concert with altimetry, satellite radiometer
velocimetry represents a technique useful for retrospective analysis of currents from high-resolution satellite radiometer
data-sets.
Received: 3 July 2001 / Accepted: 16 November 2001 相似文献
14.
液化实时监测作为减轻地震灾害的新手段,其核心技术是建立依据强震记录识别场地液化的方法,但目前所提出的方法十分有限,可靠性也缺少实际地震检验.2011年新西兰地震中液化及其震害现象显著,为检验现有液化识别方法提供了条件.目前已有并可供程使用的四种液化识别方法为:Miyajima法、Suzuki法、KY法(Kostadin... 相似文献
15.
昌平-丰南断裂是根据卫星遥感图像解译发现的一条隐伏活动断层,是NWW向张家口-蓬莱断裂带中规模最大的断裂,为进一步调查确认断裂的存在、空间位置、性质和断裂构造特征,并重新厘定其活动性,在卫星遥感影像解译断裂大体空间位置的基础上,布设了2条浅层地震勘探测线,对昌平-丰南断裂进行了高分辨率地震勘探,获得了测线控制范围内地下结构和断裂构造的清晰成像。结果表明,昌平-丰南断是一条倾向S、走向NWW的走滑正断层,浅层地震剖面揭示断层上断点埋深80~100 m,断错了上更新统底界,结合测线附近钻孔资料推测其最新活动时代为晚更新世。 相似文献
16.
利用可大范围获取的空间参数给出区域土壤液化的评估方法,可预估震前各地区土壤液化可能性,可快速评估震后震区土壤液化情况,对预防减轻地震灾害以及地震快速响应救援都具有重要意义的.本文以我国1976唐山大地震液化调查资料为背景,提出了区域土壤液化预测的四参数简化评估方法,并用2011年新西兰基督城地震进行了检验.选取场地平均剪切波速V s30、复合地形指数CTI、场地到河流的距离DR以及地面峰值加速度PGA,分别代表土壤密实程度、饱水状态、地质年代和遭遇的地震作用大小,并基于我国唐山地震液化区域调查资料生成的样本,运用经典二元Logistic回归方法,建立了区域土壤液化预测模型和评估公式,回归检验结果良好,整体回判成功率为77%,非液化和液化区域成功率分别为73%和78%.将公式应用于评估2011年新西兰基督城地震液化情况,区域液化和非液化成功率分别为82%和88%,总体成功率为84%.以上结果表明本文模型可靠,方法正确,可用于区域土壤液化震前预估以及土壤液化震后快速评估. 相似文献
17.
地震发生后，人口空间分布密度是决定救援力量部署的重要依据。然而，高精度人口空间分布数据存在获取和更新困难的问题，缺少有效的解决途径。以银川市西夏区为例，基于高空间分辨率遥感影像，通过建筑物解译与实地调查相结合的方式获取住宅建筑物信息，建立人口与住宅建筑物之间的关系模型，得到更客观真实的人口空间分布情况。研究结果表明，以高空间分辨率遥感影像解译住宅建筑物作为人口空间分布指示因子建模，得到的总体预测人口误差率为3.56%，人口平均相对误差率为9.19%，研究结果具有较高的可靠性，为震前灾害风险评估和震后灾情快速评估提供可靠的人口空间分布数据。 相似文献
18.
评估钢筋混凝土结构抗损性具有重要工程意义,但目前以单因素叠加为基础的评估方法误差较大。为解决此问题,提出基于多元模糊的钢筋混凝土结构地震抗损性评估方法。以Park-Ang地震损伤模型为前提,引入正规化累积耗能参数,得到建筑结构层间损伤表达式,加权平均获取震后建筑结构整体损伤值;利用有害层间位移角参数计算震后结构层间位移角;将获取的结构整体损伤值、层间位移角作为多因素论域,进行多元模糊结构抗损性评估,选取模糊损伤评估数学模型与隶属度函数,克服单一因素影响,计算判别因素权重与结构综合损伤指数,根据结构抗损性能判断规则得到建筑结构抗损性所属标准。经实验测试验证:基于多元模糊的钢筋混凝土结构地震抗损性评估方法精确度大于95%,评估精确性高,是一种有效的钢筋混凝土结构抗损性评估方法。 相似文献
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20.
地震液化是引起地基失稳和上部结构损害的直接原因之一,而液化震害预防的第一步就是对工程场地进行液化预测和判别。静力触探(CPT)作为最主要的原位测试技术,因其具有快速、低廉、高效等优点,被广泛用于液化判别。根据国内外近年来CPT技术的发展,对不同形式的CPT[孔压静力触探技术(CPTU)技术,电阻率孔压静力触探(RCPTU)技术、地震波孔压静力触探技术(SCPTU)技术等]在地震液化评价中的应用进行系统的论述。特别介绍一种基于状态参数进行液化判别的方法,另外还简要介绍基于概率统计分析法。比较和梳理各种液化判别方法的差异性,最后,在已有研究成果的基础上分析现有CPT液化判别法存在的问题与不足。分析结果表明:状态参数法能够同时考虑围压应力和孔隙比的影响,有效地将室内试验与现场试验联系起来;SCPTU、RCPTU液化判别框架还需进一步拓展与完善;概率统计分析法需结合相应软件使其更具适用性。 相似文献