共查询到20条相似文献，搜索用时 31 毫秒
1.
Gökhan Saygili 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2017,11(2):197-207
The conventional liquefaction potential assessment methods (also known as simplified methods) profoundly rely on empirical correlations based on observations from case histories. A probabilistic framework is developed to incorporate uncertainties in the earthquake ground motion prediction, the cyclic resistance prediction, and the cyclic demand prediction. The results of a probabilistic seismic hazard assessment, site response analyses, and liquefaction potential analyses are convolved to derive a relationship for the annual probability and return period of liquefaction. The random field spatial model is employed to quantify the spatial uncertainty associated with the in-situ measurements of geotechnical material. 相似文献
2.
The determination of seismic liquefaction potential of soil is an important task in geotechnical engineering. This article uses Minimax Probability Machine (MPM) for determination of seismic liquefaction potential of soil based on Standard Penetration Test value (N). MPM is developed based on the use of hyperplanes. It is a discriminant classifier. This study uses MPM as a classification tool. MPM uses the database collected from Chi–Chi earthquake. Two models (MODEL I and MODEL II) have been developed. MODEL I uses Cyclic Stress Ratio and N as input variables. Peck Ground Acceleration and N have been adopted as inputs for MODEL II. The performance of MODEL I and MODEL II are 97.67 and 96.51 % respectively. The performance of MODEL II is 94.11 % for the global data. The developed MPM shows good generalization capability. The results show that the developed MPM has ability for determination of seismic liquefaction potential of soil. 相似文献
3.
Assessment of seismic hazard and liquefaction potential of Gujarat based on probabilistic approaches
Gujarat is one of the fastest-growing states of India with high industrial activities coming up in major cities of the state. It is indispensable to analyse seismic hazard as the region is considered to be most seismically active in stable continental region of India. The Bhuj earthquake of 2001 has caused extensive damage in terms of causality and economic loss. In the present study, the seismic hazard of Gujarat evaluated using a probabilistic approach with the use of logic tree framework that minimizes the uncertainties in hazard assessment. The peak horizontal acceleration (PHA) and spectral acceleration (Sa) values were evaluated for 10 and 2?% probability of exceedance in 50?years. Two important geotechnical effects of earthquakes, site amplification and liquefaction, are also evaluated, considering site characterization based on site classes. The liquefaction return period for the entire state of Gujarat is evaluated using a performance-based approach. The maps of PHA and PGA values prepared in this study are very useful for seismic hazard mitigation of the region in future. 相似文献
4.
The performance-based liquefaction potential analysis was carried out in the present study to estimate the liquefaction return
period for Bangalore, India, through a probabilistic approach. In this approach, the entire range of peak ground acceleration
(PGA) and earthquake magnitudes was used in the evaluation of liquefaction return period. The seismic hazard analysis for
the study area was done using probabilistic approach to evaluate the peak horizontal acceleration at bed rock level. Based
on the results of the multichannel analysis of surface wave, it was found that the study area belonged to site class D. The
PGA values for the study area were evaluated for site class D by considering the local site effects. The soil resistance for
the study area was characterized using the standard penetration test (SPT) values obtained from 450 boreholes. These SPT data
along with the PGA values obtained from the probabilistic seismic hazard analysis were used to evaluate the liquefaction return
period for the study area. The contour plot showing the spatial variation of factor of safety against liquefaction and the
corrected SPT values required for preventing liquefaction for a return period of 475 years at depths of 3 and 6 m are presented
in this paper. The entire process of liquefaction potential evaluation, starting from collection of earthquake data, identifying
the seismic sources, evaluation of seismic hazard and the assessment of liquefaction return period were carried out, and the
entire analysis was done based on the probabilistic approach. 相似文献
5.
This paper highlights the seismic microzonation carried out for a nuclear power plant site. Nuclear power plants are considered to be one of the most important and critical structures designed to withstand all natural disasters. Seismic microzonation is a process of demarcating a region into individual areas having different levels of various seismic hazards. This will help in identifying regions having high seismic hazard which is vital for engineering design and land-use planning. The main objective of this paper is to carry out the seismic microzonation of a nuclear power plant site situated in the east coast of South India, based on the spatial distribution of the hazard index value. The hazard index represents the consolidated effect of all major earthquake hazards and hazard influencing parameters. The present work will provide new directions for assessing the seismic hazards of new power plant sites in the country. Major seismic hazards considered for the evaluation of the hazard index are (1) intensity of ground shaking at bedrock, (2) site amplification, (3) liquefaction potential and (4) the predominant frequency of the earthquake motion at the surface. The intensity of ground shaking in terms of peak horizontal acceleration (PHA) was estimated for the study area using both deterministic and probabilistic approaches with logic tree methodology. The site characterization of the study area has been carried out using the multichannel analysis of surface waves test and available borehole data. One-dimensional ground response analysis was carried out at major locations within the study area for evaluating PHA and spectral accelerations at the ground surface. Based on the standard penetration test data, deterministic as well as probabilistic liquefaction hazard analysis has been carried out for the entire study area. Finally, all the major earthquake hazards estimated above, and other significant parameters representing local geology were integrated using the analytic hierarchy process and hazard index map for the study area was prepared. Maps showing the spatial variation of seismic hazards (intensity of ground shaking, liquefaction potential and predominant frequency) and hazard index are presented in this work. 相似文献
6.
采用组件式GIS (COMGIS)技术开发了结合BP神经网络分析模型的场地地震液化势评价系统,调用水平成层土地震反应分析程序SHAKE91实现设定地震下地震动影响场的模拟。在VB下调用Matlab神经网络工具箱来完成场地地震液化势评价模型在COMGIS系统中的模块化;利用GIS技术对评价结果,即液化势等级进行空间复合,给出场地潜在的地层液化势空间分布图。研究表明,SHAKE91应用程序在系统菜单下可直接调用,实现地震动影响场计算的模块化;BP神经网络技术应用于场地地震液化势评价中能达到较为理想的效果;系统的GIS空间分析功能可使评价结果与场地信息进行空间匹配,实现目标场地潜在地震液化势的快速评估。 相似文献
7.
以剪切波速与地表峰值加速度为依据的地震液化确定性及概率判别法 总被引：2，自引：0，他引：2
剪切波速作为土性的基本参数,为评价土体抵抗地震液化的能力提供了一种方法。回顾了以剪切波速和地表峰值加速度为依据的场地地震液化判别方法的演化历史,依据他人收集的现场液化资料,合计49次地震、618例液化/不液化场地数据,提出了确定液化临界曲线的基本原则,给出了基于修正剪切波速与地表峰值加速度的液化临界曲线,验证了液化临界曲线的位置对细粒含量、有效上覆压力、震级等因素取值变化的合理性,分析了估计土层循环应力比CSR的剪应力折减系数、震级标定系数、有效上覆压力修正系数等因素的不确定性对液化临界曲线的敏感性。结果表明：液化临界曲线对各种影响因素具有很好的适用性。利用Monte Carlo模拟、加权最大似然法和加权经验概率法,给出了建议的液化临界曲线的名义抗液化安全系数与液化概率的经验关系式及概率等值线,并对核电厂Ⅰ类、Ⅱ类和Ⅲ类抗震物项地基,分别建议了相应的液化临界曲线。该方法以丰富的现场液化数据为依据,具有广泛的应用前景。 相似文献
8.
现有液化识别方法对比分析 总被引：1，自引：0，他引：1
场地液化实时监测和报警是减轻液化灾害的新途径,其核心技术是建立依据强震记录对液化场地进行反演识别的方法。采用统一样本,其中尽可能多地包含软土场地地震动记录,按场地类别对目前国内外现有的Suzuki法、Miyajima法、KY法和SY法等4种主要液化识别方法的可靠性进行了对比分析,提出评价结果及改进建议。分析表明：对全部样本,SY法、Suzuki法、KY法和Miyajima法识别成功率依次为98%、85%、77%和52%;Suzuki法、KY法和Miyajima法的成功率受场地类别影响显著,随场地变软而明显降低,对D类场地识别成功率均在55%以下;Suzuki法、Miyajima法和KY法均采用与绝对周期相关的参数作为判别指标,而软土与液化场地上存在明显交叉,极易导致误判;SY法选取地震动参数的相对变化作为识别指标,即使对D类场地成功率也达到92%,但其方法中仍有若干细节需要进一步探讨和改进 相似文献
9.
以标贯试验为依据的砂土液化确定性及概率判别法 总被引：1，自引：0，他引：1
核电厂址非基岩场地的地基液化问题是核电厂选址的关键问题,亟需建立核电厂址地基液化判别方法。回顾了以标贯试验和地表峰值加速度为依据的砂土液化判别方法的演化历史,依据Idriss-Boulanger确定液化临界曲线的基本方法,提出了确定液化临界曲线的基本原则,分别依据美国液化数据库、中国抗震规范液化判别式所用的液化数据及综合两者的液化数据资料,给出了相应的液化临界曲线,验证了液化临界曲线的位置对不同的细粒含量、有效上覆压力、现场试验方法的液化数据的合理性,分析了测量或估计土层循环应力比和修正标贯击数各种因素的不确定性对液化临界曲线的敏感性,结果表明：所提的液化临界曲线不易受各种因素的影响。利用Monte Carlo模拟、加权最大似然法和加权经验概率法,给出了液化临界曲线的名义抗液化安全系数与液化概率的经验关系式及概率等值线,并对核电厂Ⅰ类、Ⅱ类和Ⅲ类抗震物项地基,给出了相应的液化临界曲线。 相似文献
10.
场地液化实时监测是减轻地震灾害的新手段,其核心是建立依据强震记录识别场地液化技术,但目前建立的方法尚不成熟,可靠性也缺少实际地震的检验。2011年新西兰地震中液化及其震害现象显著,为检测现有液化识别方法提供了条件。利用该次强震记录,采用孙锐和袁晓铭以往提出的频率下降率法对记录场地液化进行了盲测,为今后方法改进提供思路。针对震中距小于50 km的全部27条原始强震记录进行了识别,有9个场地识别为液化场地,其余为非液化场地;对两个已报道为液化的场地,频率下降率法给出了正确的识别结果;识别出的液化场地主要集中在克赖斯特彻奇市东侧Avon河两岸,这一结果与报导定性相符;发现有两个场地原始强震记录存在疑点,经处理后给出了修正结果。 相似文献
11.
A seismic hazard analysis was conducted in Laoag City, Northern Philippines to determine the design ground motion for liquefaction potential assessment of the area. Because the hazard analysis was done within the framework of liquefaction potential assessment, only those earthquakes with magnitude–distance combinations that are capable of generating liquefaction were considered in the study. Both probabilistic and deterministic approaches were used in the analysis. From the results of the probabilistic analysis, seismic hazard curves were generated from which the ground motion with a 10% probability of exceedance in 50years was obtained. This was then modified in consideration of the soft soil condition in the study area. Deaggregation was performed to determine the most likely earthquake to generate the said level of ground shaking. 相似文献
12.
This article describes a new performance-based approach for evaluating the return period of seismic soil liquefaction based on standard penetration test (SPT) and cone penetration test (CPT) data. The conventional liquefaction evaluation methods consider a single acceleration level and magnitude and these approaches fail to take into account the uncertainty in earthquake loading. The seismic hazard analysis based on the probabilistic method clearly shows that a particular acceleration value is being contributed by different magnitudes with varying probability. In the new method presented in this article, the entire range of ground shaking and the entire range of earthquake magnitude are considered and the liquefaction return period is evaluated based on the SPT and CPT data. This article explains the performance-based methodology for the liquefaction analysis – starting from probabilistic seismic hazard analysis (PSHA) for the evaluation of seismic hazard and the performance-based method to evaluate the liquefaction return period. A case study has been done for Bangalore, India, based on SPT data and converted CPT values. The comparison of results obtained from both the methods have been presented. In an area of 220 km2 in Bangalore city, the site class was assessed based on large number of borehole data and 58 Multi-channel analysis of surface wave survey. Using the site class and peak acceleration at rock depth from PSHA, the peak ground acceleration at the ground surface was estimated using probabilistic approach. The liquefaction analysis was done based on 450 borehole data obtained in the study area. The results of CPT match well with the results obtained from similar analysis with SPT data. 相似文献
13.
Chang-Guk Sun 《Environmental Earth Sciences》2012,65(7):1987-2001
A geotechnical information system (GTIS) was constructed within a spatial geographic information system (GIS) framework to
reliably predict geotechnical information and accurately estimate site effects at Gyeongju, an urban area in South Korea.
The system was built based on both collected and performed site investigation data in addition to acquired geo-knowledge data.
Seismic zoning maps were constructed using the site period (T
G) and mean shear wave velocity to a depth of 30 m (V
S30), and these maps were presented as a regional strategy to mitigate earthquake-induced risks in the study area. In particular,
the T
G distribution map indicated the susceptibility to ground motion resonance in periods ranging from 0.2 to 0.5 s and the corresponding
seismic vulnerability of buildings with two to five stories. Seismic zonation of site classification according to V
S30 values was also performed to determine the site amplification coefficients for seismic design and seismic performance evaluation
at any site and administrative subunit in the study area. In addition, we investigated the site effects according to subsurface
and surface ground irregularities at Gyeongju by seismic response analyses in time domains based on both two- and three-dimensional
spatial finite element models, which were generated using spatial interface coordinates between geotechnical subsurface layers
predicted by the GTIS. This practical study verified that spatial GIS-based geotechnical information can be a very useful
resource in determining how to best mitigate seismic hazards, particularly in urban areas. 相似文献
14.
根据地球物理探测、海底取样、钻探及现场测试等实测资料详细分析，发现粤港澳跨海大桥海域具有独特的自然条件以及复杂的海洋工程地质特征。海底地形地貌较为复杂，存在含浅层气区、活动性断层、沙波、地震活动、不规则基岩、埋藏古河道、冲刷槽沟和水下浅滩等潜在灾害地质因素，尤其粤港澳跨海大桥是特大型建筑，它经过的海域分布着多种潜在的地质灾害，应引起重视。 相似文献
15.
This paper is a follow-up to a previous paper on the subject of liquefaction potential index (LPI), a parameter that is often used to characterize the potential for surface manifestation of liquefaction at a given site subjected to a given shaking level (represented by a pair of peak ground surface acceleration amax and moment magnitude Mw). In the previous paper by Juang and his coworkers, the LPI was re-calibrated for a piezocone penetration test (CPTU) model, and a simplified model based on LPI was created for computing the conditional probability of surface manifestation of liquefaction (PG). In this paper, the model for this conditional probability PG is extended into a complete framework for assessing the probability of surface manifestation of liquefaction in a given exposure time at a given site subjected to all possible ground motions at all seismic hazard levels. This new framework is formulated and demonstrated with an example site in 10 different seismic regions in the United States. 相似文献
16.
Engineering geological and geotechnical site characteristics were assessed and seismic hazard studies performed for the Upper
Pliocene to Pleistocene fluvial and Quaternary alluvial and terrace deposits for a site west of Ankara, Turkey. Sediment conditions
were determined and a soil profile was characterized by surface geophysical methods. These studies were integrated with existing
in-situ characterization studies to create a seismic and geotechnical database for the site. A seismic zonation map of the
site was then prepared. Site classification systems were assigned to account for site effects in relation to seismic hazard
assessments. The consequences of the seismic hazards were investigated and recommendations were presented. 相似文献
17.
地震滑坡危险性概念和基于力学模型的评估方法探讨 总被引：1，自引：0，他引：1
在我国大陆地区运用基于力学模型的Newmark位移分析方法开展地震滑坡危险性定量评估,尚处在起步阶段.为了进一步明确地震滑坡危险性概念和改进推广基于力学模型的评估方法,首先阐明了狭义的地震滑坡危险性预测评估与震后反演评估的关系; 同时为了应对地震应急、震后重建及潜在地震条件下的不同评估需求,初步提出了广义的地震滑坡危险性评估框架.随后申述了基于Newmark位移分析的地震滑坡危险性评估方法的理论基础、方法分类及最新进展,并以汶川地震滑坡危险性快速评估为例,剖析了目前影响评估有效性的不确定性及空间数据质量等问题,指出了基于力学模型的地震滑坡危险性评估方法的改进方向.建议开展潜在地震及其诱发滑坡危险性的耦合评估,建立适用于我国大陆地区地震滑坡位移分析的经验模型,以便为国家层面的地震滑坡危险性区划服务. 相似文献
18.
基于简化 Newmark位移模型的区域地震滑坡危险性快速评估以汶川MS 8.0级地震为例 总被引：1，自引：0，他引：1
以汶川MS8.0级地震重灾区的11县市为例,初步提出了基于简化Newmark位移模型的地震滑坡危险性应急快速评估方法。利用汶川地震即时地震动参数、工程地质岩性经验分组及地形坡度数据,借助ArcGIS空间数据建模工具编制了地震滑坡危险性快速评估流程模块。计算了区域浅表层饱和岩土体斜坡的静态安全系数Fs、临界加速度ac,并借此分析了地震滑坡易发性。利用经验式获得了汶川地震Arias强度和区域滑坡位移DN分布,实现了汶川地震重灾区地震滑坡危险性的快速评估,为应急救灾决策提供了参考。通过对比评估结果和震后滑坡调查成果,可知数十处灾难性滑坡绝大部分位于-高危险区的龙门山主中央断裂带两侧约20km地带中,显示了评估方法的可靠性; 同时,分析指出了空间数据精度及更新不足导致局部评估结果欠佳的局限性,并提出了改进建议。 相似文献
19.
Chih-Chieh Lu Jin-Hung Hwang C. Hsein Juang Chih-Sheng Ku Zhe Luo 《Engineering Geology》2009,108(1-2):24-35
This paper presents a framework for assessing the probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time. This framework deals not only with the effect of liquefaction (in terms of settlement) but also with probabilistic characterization of all possible ground motions at a given site (in terms of a joint distribution of amax and Mw). Additionally, a new concept, referred to herein as liquefaction-induced settlement hazard curve, is introduced for assessing the annual rate of settlement exceedance at a given site. This settlement hazard curve concept has the potential to be a very useful tool in the field of geotechnical earthquake engineering. Satisfactory results are obtained in the demonstration examples analyzed with the proposed framework. Whereas the proposed framework is simple and effective, further refinements to this framework, especially on the treatment of epistemic uncertainty, are warranted. 相似文献
20.
The town of Edessa is located on Northern Greece at a region that is characterized as low seismicity zone due to the fact
that few moderate events of M < 6 occurred during the last century. According to the Greek Seismic Code, the expected acceleration having a 10% probability
of being exceeded in 50 years is equal to 0.16g. However, an amplification of ground motion is likely to occur due the local geology that is consisted of Holocene fluvio-torrential
deposits. The basic aim of this paper is to evaluate the site amplification due to geological conditions and to assess the
liquefaction hazard. In order to achieve this, 1-D site response analyses were performed. The data that were employed for
the construction of the numerical models have been collected from borings with standard penetrations tests (SPT) that were
drilled for construction purposes. Afterward, the liquefaction potential of the subsoil layers was evaluated taking into consideration
two seismic scenarios. The first scenario was based on the seismic parameters, earthquake magnitude and PGA, assigned by the
Greek Seismic Code. On the second seismic model, we employed the values of acceleration, resulted from the 1-D analyses and
the earthquake magnitude as it was defined by the Greek Seismic Code. In order to compile the liquefaction hazard maps, we
initially estimated the liquefaction potential index (LPI) of the soil columns using the parameters provided by SPT, for both
seismic loadings, and afterward we correlated these values with the proposed classification of the severity of liquefaction-induced
deformations. In addition, having computed the value of probability based on the LPI, liquefaction manifestations probability
maps were compiled for both scenarios. The result of this study was that liquefaction-induced ground disruptions are likely
to occur at the center of the city, among the branches of Voda River, only when the amplified values of acceleration are taken
into account to the computation of liquefaction potential. 相似文献