PDIF震相在嘉峪关地震台的记录特征分析

本文用数例典型地震记录到的PDIF震相总结美洲沿岸近海地震在嘉峪关台的记录特征,分析说明PDIF震相的出现规律及特征。运用笔者多年来工作中积累的震相分析经验,可更好地指导观测人员对极远震震相的分析工作,以便加强分析队伍的分析认知能力。     

Pdif震相在CDSN兰州地震台的记录特征

通过对CDSN兰州地震台1990-2000年间31个极远震记录的分析,得到了Pdif震相在CDSN宽频带数字地震仪上的运动学和动力学特征;给出了兰州地震台Pdif震相走时便查表,以便分析时查询比较.所得结果有助于提高地震速报能力和积累震相分析经验,有助于对核幔边界物理性质的认识.     

攀枝花地震台数字地震分析探讨

结合地震波记录原理,分析并讨论攀枝花台数字仪震相的一些物理特征,并使用MATLAB对攀枝花、长春台的地震资料做简单滤波分析,便于真实地反映地震波震相。参考川滇交界地区地质构造,总结出攀枝花台对多次地震记录震相分析的经验规律,为地震速报快速识别震相提供实用参考。     

浅源极远震的震相特征与识别方法

介绍了纵波在地球内部的传播过程和浅源极远震的震相特点。由不同震中距的地震反映在三分向地震记录图上的初至震相振幅比的差异,归纳出由地震初动判别地震类型的方法,结合实际工作经验,得出如何判别ＰＫＳ震相、如何由ＰＰ推Ｓ、由ＳＳ反推ＰＰ震相,以及根据地震面波的到时,通过《Ｒｍ－Ｐ》表来验证震中距等几种识别极远震及其震相的方法。     

Pdif震相的记录特征

通过对北京地震台1990-2008年间63个极远震记录的分析,简要讨论Pdif震相在CDSN 宽频带数字仪器上的记录特征.目前,北京地震台观测到的Pdif震相的记录范围约101.87°—172.18°,最小震级为6.0级,最浅震源深度为9 km,最深为631.3 km.所得结果有助于提高地震速报能力和积累震相分析经验,...     

昆仑山西口Ms8.1特大地震序列的记录特征

新疆,青海两省交界地处喜马拉雅山地震带,即昆仑山西口,是我国西部强震频发地区.2001年11月14日发生在36.2°N,90.9°E的8.1级大地震及其余震序列,因震中距高台基准地震台较近,可见模拟记录已全部限幅,无法进行震相分析,又由于地震震相特殊,在数字化仪(VBB)上很难找到震相的准确到时,影响了高台基准地震台的速报速度和分析精度.震后,经对其主震和大量余震进行仔细分析讨论后,对该地区地震震相分析得出了一些经验提供给同行们.     

鹤岗地震台测震观测资料质量分析与研究

通过对鹤岗地震台测震观测资料和国家测震观测资料评比标准进行分析比较,在保证观测仪器正常运转的情况下,认为要提高鹤岗地震台测震观测资料质量,就要做好震相分析、震级测定、数据报送、单台报告四方面的工作,其中震相分析精度是保证观测资料质量的关键,而初至波震相的精度决定了震相分析的精度,所以对如何提高初至波震相精度进行了分析,并提出了几点改善工作的建议。     

浅析巴里坤台记录的兴都库什地震震相特征及sP震相与震源深度的关系

以巴里坤台记录的兴都库什地区2004～2019年发生的138次MW≥5.0地震为研究对象,通过分析其震相特征及sP-P到时差与震源深度的关系,为该地区地震的震相分析和震源深度计算提供参考.结果表明:① 兴都库什地区地震震相以P、sP、S为主,少数震例可记录到pP、sS或ScS震相.② 兴都库什地区地震以中深源地震为主,...     

对介休小震群震相的识别

在地震记录图分析中,弱震和爆破的震相是较难区别的.笔者通过对介休地震台记录的小震群弱震震相的识别,受到启示,从而提高了对该区地震震相分析的鉴别能力.     

数字地震信号震相自动识别研究

震相识别是从地震记录中获取震源空间位置、震源破裂过程和地球介质结构等信息的前提.由于震相形态复杂多变,目前的识别都靠人工完成,不仅经验性强、工作量大,而且造成地震观测工作难以实现自动化.若能自动识别震相,更多的人就可直接使用地震记录获取信息,减轻震相识别人员的工作量,并使地震观测工作实现自动化成为可能.     

Comparison of the sector and conventional spherical harmonic analyses of the solar magnetic field on the photosphere,source surface,and in the Earth’s orbit on July 10–20, 2004

The results of a spherical harmonic analysis and a sector spherical harmonic analysis of the solar magnetic field on the photosphere, source surface, and in the Earth’s orbit on July 10–20, 2004, were compared. It was found that the field values according to a sector harmonic analysis are an order of magnitude as large as the same values according to a spherical harmonic analysis and differ in the configuration. A twocomponent magnetic field structure was revealed: short-range sources are better described by a sector spherical harmonic analysis; long-range sources are better described by a spherical harmonic analysis. This is caused by the different depths of the occurrence of sources below the photosphere.     

地震作用下边坡稳定性分析方法

地震引起的滑坡已成为大地震引起的严重次生灾害现象,如2008年汶川地震引起的滑坡灾害．本文对地震作用下边坡稳定性分析的研究现状及特点进行了分析总结．地震边坡稳定性分析方法总体上可分为定性分析和定量分析两类．本文分别从工程地质与灾害调查分析、 灾害调查与地震烈度及地震动参数的统计分析、 简化模型理论分析、 数值计算分析和模型试验分析等方面,介绍了相应边坡稳定性分析理论和方法的提出及其沿革,分析了不同理论和方法的特点及适应性,并进一步提出了相关研究存在的问题和发展趋势．      

扭转不规则结构水平侧向力分布模式与pushover分析

水平侧向力分布模式的施加问题是合理进行pushover分析的关键环节。对于可以简化为平面模型的结构,传统的水平侧向力分布模式表现出较好的适用性,但对于因扭转不规则而导致必须采用空间模型的结构则并不适用。为此,针对扭转不规则结构的水平侧向力分布模式问题,并基于该类结构的地震响应特征,通过引入水平侧向力调整系数和水平侧向力分配系数,提出了扭转不规则结构改进的水平侧向力分布模式。对一具有典型扭转不规则特性的空间钢框架结构分别进行改进分布模式下的pushover分析和IV类场地典型地震动作用下的弹塑性时程分析,计算结果显示:改进分布模式下的pushover分析体现出扭转效应对结构反应的影响,并在一定程度上反映出更多的结构抗震信息,验证了所提出模式的可行性,说明pushover分析法也同样适用于扭转不规则结构。     

高层建筑筒体结构动力分析的新方法

主要研究简体结构动力分析的新方法，先利用QR法建立了简体结构的新动力模型，然后利用5次样条加权残数法建立了求解动力模型的新算法，最后提出了高层与超高层建筑结构动力分析的新方法，文中附有算例。     

Sensitivity analysis of the probability distribution of groundwater level series based on information entropy

Information entropy is an effective method to analyze uncertainty in various processes. The principle of maximum entropy (POME) provides a guide line for the parameter estimation of probability density function (PDF). Mutual entropy analysis is well qualified for delineating the nonlinear and complex multivariable relationship. The probability distribution of model output is the element of model uncertainty analysis. In this paper, a synthetic groundwater flow field is build to produce groundwater level series (GLS). The probability distribution of GLS is obtained by the frequency analysis method based on POME and Chi-Squared test. The important uncertainty factors that affect the parameters of PDF of GLS are assessed by the sensitivity analysis methods, which include stepwise regression analysis and mutual entropy analysis. Results of this analysis indicate that most of the GLS follow normal distribution (or log-normal distribution), while a few obey others. The mean and variance of normal GLS are affected differently by the input variables of groundwater model. Mutual entropy analysis is more competitive and appropriate for delineating the nonlinear and nonmonotonic multivariable relationship than stepwise regression analysis.     

Seismic analysis of sliding wedge: extended Francais–Culmann's analysis

Pseudo-static analysis is commonly used to design earth structures. Most pseudo-static methods of analysis require a computer program. This paper presents a simple closed form solution of seismic stability analysis by extending Francais–Culmann's analysis. The analysis is valid for a slope with the most critical planar mechanism and under the influence of horizontal and vertical earthquake accelerations. The resulting permanent displacement is discussed and demonstrated using several real earthquake records. The simplicity of extended Francais–Culmann's solution allows it to be used for preliminary design and classroom instruction.     

Fast velocity analysis by wave path migration

Iterative migration velocity analysis is computationally expensive, where most of the computation time is used for generating prestack depth images. By using a reduced form of Kirchhoff migration, denoted as wave path migration, we can significantly speed up the depth imaging process and reduce the entire velocity analysis expense accordingly. Our results with 2D synthetic and field data show that wave path migration velocity analysis can efficiently improve the velocity model and the wave path migration velocity analysis updated velocity correlates well with that from the Kirchhoff migration velocity analysis. The central processing unit comparison shows that, for a 2D synthetic and field data set, wave path migration velocity analysis is six times faster than Kirchhoff migration velocity analysis. This efficiency should be even greater for 3D data.     

基于小波分析的结构损伤检测研究进展

近10几年来,在土木和机械领域结构损伤识别方法已引起不同领域的相关学者的极大研究兴趣。小波分析是一种新的数学分析和信号处理工具,可以对非稳态信号进行详细的时频分析,是传统傅里叶分析所不能及的,已广泛应用于土木、机械和航空工程领域中,特别是在结构损伤识别和健康监测中的应用尤为突出。本文回顾和总结了小波分析理论及其在结构损伤识别、损伤定位和损伤程度确定中的应用,对今后的研究进行了讨论和展望。     

Benchmark Analysis of Solute Transport with Multiaquifer Wells

A benchmark analysis is developed for assessing the reliability of the representation of multiaquifer wells in numerical solute transport simulators. The analysis considers the installation of a well that penetrates two aquifers that are otherwise isolated. The interconnection of the two aquifers by the multiaquifer well leads to the capture of a plume in an upper aquifer and the development of a plume in a lower aquifer. The benchmark analysis couples an exact Laplace transform solution for radially convergent transport with a generalization of an exact Laplace transform solution for radially divergent transport. The benchmark analysis is used to test the multiaquifer well simulation capability incorporated recently in MT3DMS. The results of the analysis provide insights into important issues of model accuracy and efficiency. The results of the analysis also highlight the potential implications of installing wells with relatively long screens at sites with contaminated groundwater.     

Risk and uncertainty analysis of gas pipeline failure and gas combustion consequence

Taking into account a general concept of risk parameters and knowing that natural gas provides very significant portion of energy, firstly, it is important to insure that the infrastructure remains as robust and reliable as possible. For this purpose, authors present available statistical information and probabilistic analysis related to failures of natural gas pipelines. Presented historical failure data is used to model age-dependent reliability of pipelines in terms of Bayesian methods, which have advantages of being capable to manage scarcity and rareness of data and of being easily interpretable for engineers. The performed probabilistic analysis enables to investigate uncertainty and failure rates of pipelines when age-dependence is significant and when it is not relevant. The results of age-dependent modeling and analysis of gas pipeline reliability and uncertainty are applied to estimate frequency of combustions due to natural gas release when pipeline failure occurs. Estimated age-dependent combustion frequency is compared and proposed to be used instead of conservative and age-independent estimate. The rupture of a high-pressure natural gas pipeline can lead to consequences that can pose a significant threat to people and property in the close vicinity to the pipeline fault location. The dominant hazard is combustion and thermal radiation from a sustained fire. The second purpose of the paper is to present the combustion consequence assessment and application of probabilistic uncertainty analysis for modeling of gas pipeline combustion effects. The related work includes performance of the following tasks: to study gas pipeline combustion model, to identify uncertainty of model inputs noting their variation range, and to apply uncertainty and sensitivity analysis for results of this model. The performed uncertainty analysis is the part of safety assessment that focuses on the combustion consequence analysis. Important components of such uncertainty analysis are qualitative and quantitative analysis that identifies the most uncertain parameters of combustion model, assessment of uncertainty, analysis of the impact of uncertain parameters on the modeling results, and communication of the results’ uncertainty. As outcome of uncertainty analysis the tolerance limits and distribution function of thermal radiation intensity are given. The measures of uncertainty and sensitivity analysis were estimated and outcomes presented applying software system for uncertainty and sensitivity analysis. Conclusions on the importance of the parameters and sensitivity of the results are obtained using a linear approximation of the model under analysis. The outcome of sensitivity analysis confirms that distance from the fire center has the greatest influence on the heat flux caused by gas pipeline combustion.