工程爆破场地地震动强度预测研究

本文介绍了爆破地震动强度的预测方法和该领域研究的国内外现状,以岭澳核电站场地为例,利用该场地土石方工程爆破时实监测获得的大量实验数据进行统计回归分析,提出了一种估计(折算)爆破药量的方法,给出预测爆破地震动加速度、速度、的经验公式。按此地震动衰减规律并结合时实监测数据指导爆破,确保大亚湾核电站的安全运行。这种折算爆破药量的方法和预测爆破地震动强度的经验公式对指导工程爆破具有重要参考价值。     

地震动输入能量衰减规律的研究

对所收集到的266条强震记录，将其按场地条件分类，计算了不同场地条件、不同延性系数下的“绝对”和“相对”输入能量反应谱，然后利用两步回归法，得出了不同场地条件下地震动“绝对”和“相对”两种输入能量的衰减规律，分析了场地条件、延性系数、震级及距离等参数对地震动能量谱的影响，并对两种输入能量衰减规律进行了比较。     

中小震近场地震动估计中地震动衰减关系的适用性分析

核工程场地设计基准地震动确定中涉及弥散地震的地震动估计，这导致中小震近场地震动估计成为被关注的研究课题。本文基于一些中小震近场地震动记录资料，分析和探讨了国内外多种地震动衰减关系对中小震近场地震动估计的适用性问题，并结合我国几个核工程地震问题研究工作的实践对中小震近场地震动衰减关系确定的思路和原则提出了建议。     

中强地震活动区地震动衰减关系的确定

地震动衰减关系是影响地震安全性评价特别是地震区划结果的重要因素.我国现行的地震动衰减关系主要是依据6级以上地震的地面运动资料得到的,并没有考虑中强地震的衰减特性.为此,文中利用现有的烈度资料和其他可供参考的研究成果来建立我国中强地震活动区的地震动衰减关系.收集了我国华中、华南、东北等地区的51次地震的烈度等震线资料,运用单随机变量加权最小二乘回归法得到中强地震活动区烈度衰减关系.然后以美国西部地区为参考地区,运用缺乏地震动参数的地震动估计方法-地震对映射法得到中强地震活动区峰值加速度和有效峰值加速度衰减关系.最后,通过与我国强地震区和中强地震区已有的烈度衰减关系和地震动衰减关系的对比,验证了得出的我国中强地震活动区烈度衰减关系和地震动衰减关系的合理性.     

近断层地震动的基本特征

本文对近断层地震动的基本特征作了详细分析,这些基本特征主要包括近断层强地震动的集中性、地表破裂、地面永久变形、破裂的方向性效应、近断层速度大脉冲和上盘效应。这些特征虽然在一次地震中不一定同时出现,但它们是已经被强震观测资料和数值模拟证实了的,在模拟和预测近断层地震动时,必须充分考虑这些特点,合理的近断层地震动模拟或预测模型和方法应当在结果中再现这些特点。     

Development of attenuation relation for the near fault ground motion from the characteristic earthquake

A composite source model has been used to simulate a broadband strong ground motion with an associated fault rupture process. A scenario earthquake fault model has been used to generate 1 000 earthquake events with a magni-tude of Mw8.0. The simulated results show that, for the characteristic event with a strike-slip faulting, the character istics of near fault ground motion is strongly dependent on the rupture directivity. If the distance between the sites and fault was given, the ground motion in the forward direction (Site A) is much larger than that in the backward direction (Site C) and that close to the fault (Site B). The SH waves radiated from the fault, which corresponds to the fault-normal component plays a key role in the ground motion amplification. Corresponding to the sites A, B, and C, the statistical analysis shows that the ratio of their aPG is 2.15:1.5:1 and their standard deviations are about 0.12, 0.11, and 0.13, respectively. If these results are applied in the current probabilistic seismic hazard analysis (PSHA), then, for the lower annual frequency of exceedance of peak ground acceleration, the predicted aPG from the hazard curve could reduce by 30% or more compared with the current PSHA model used in the developing of seismic hazard map in the USA. Therefore, with a consideration of near fault ground motion caused by the rupture directivity, the regression model used in the development of the regional attenuation relation should be modified accordingly.     

地震动衰减关系拟合的新两步法

本文根据地震动衰减的理论分析结果和强震观测记录，提出了一种新的拟合地震动衰减关系的两步法，并用新近补充，完善的美国西部强震记录，对PGA，EPA和EPV衰减特性进行了分析，结果表明，建议的方法能反映近场强震地震动饱和效应和大震远场衰减的特点。     

A ground motion prediction equation for JMA instrumental seismic intensity for shallow crustal earthquakes in active tectonic regimes

The JMA (Japan Meteorological Agency) seismic intensity scale has been used in Japan as a measure of earthquake ground shaking effects since 1949. It has traditionally been assessed after an earthquake based on the judgment of JMA officials. In 1996 the scale was revised as an instrumental seismic intensity measure (I_JMA) that could be used to rapidly assess the expected damage after an earthquake without having to conduct a survey. Since its revision, Japanese researchers have developed several ground motion prediction equations (GMPEs) for I_JMA using Japanese ground motion data. In this paper, we develop a new empirical GMPE for I_JMA based on the strong motion database and functional forms used to develop similar GMPEs for peak response parameters as part of the PEER (Pacific Earthquake Engineering Research Center) Next Generation Attenuation (NGA) project. We consider this relationship to be valid for shallow crustal earthquakes in active tectonic regimes for moment magnitudes ( M ) ranging from 5.0 up to 7.5–8.5 (depending on fault mechanism) and rupture distances ranging from 0 to 200 km. A comparison of this GMPE with relationships developed by Japanese researchers for crustal and shallow subduction earthquakes shows relatively good agreement among all of the relationships at M 7.0 but relatively poor agreement at small magnitudes. Our GMPE predicts the highest intensities at small magnitudes, which together with research on other ground motion parameters, indicates that it provides conservative or upwardly biased estimates of I_JMA for M <5.5. Copyright © 2010 John Wiley & Sons, Ltd.     

Attenuation of peak ground accelerations from the great Wenchuan earthquake

Over 800 accelerograms recorded by 272 ground-level stations during the Wenchuan earthquake are used to analyze the influence of rupture distance, local site conditions and azimuth on peak ground accelerations (PGAs). To achieve a better understanding of the characteristics of ground motions, the spatial distributions of the EW, NS and UD components of PGAs arc obtained. Comparisons between the EW and NS components, the fault-normal and fault-parallel components,and the vertical and horizontal components of PGAs are performed, and the regression formula of the vertical-to-horizontal ratio of PGAs is developed. The attenuation relationship of peak horizontal accelerations (PHAs) is compared with several contemporary attenuation relationships. In addition, an analysis of residuals is conducted to identify the potential effects of rupture distance, azimuth and site conditions on the observed values of PHAs. The analysis focuses on medium-hard soil site conditions, as they provided most of the data used in this study.     

Orientation effect on ground motion measurement for Mexican subduction earthquakes

The existence of the principal directions of the ground motion based on Arias intensity is well-known. These principal directions do not necessarily coincide with the orientations of recording sensors or with the orientations along which the ground motion parameters such as the peak ground acceleration and the pseudo-spectral acceleration (PSA) are maximum. This is evidenced by the fact that the maximum PSA at different natural vibration periods for horizontal excitations do not correspond to the same orientation. A recent analysis carried out for California earthquake records suggests that an orientation-dependent ground motion measurement for horizontal excitations can be developed. The main objective of this study is to investigate and provide seismic ground motion measurements in the horizontal plane, including bidirectional horizontal ground motions, for Mexican interplate and inslab earthquake records. Extensive statistical analyses of PSA are conducted for the assessment, The analysis results suggest that similar to the case of California records, the average behavior of the ratio of the PSA to the maximum resulting PSA can be approximated by a quarter of an ellipse in one quadrant; and that the ratio can be considered to be independent of the value of the maximum resulting PSA, earthquake magnitude, earthquake distance and the focal depth. Sets of response ratios and attenuation relationships that can be used to represent a bidirectional horizontal ground motion measurement for Mexican interplate and inslab earthquakes were also developed.     

A study of design spectra based on attenuation relationship of ground motion

In recent years, more and more studies are focused on the performance in seismic design instead of the strength of structures. People have realized that the structure deformation (displacement) can describe the damage more properly and directly than the strength (force). The displacement design spectra need to be constructed within more wide range of the period and the damping for the displacement-based seismic design.     

Effect of seismic super-shear rupture on the directivity of ground motion acceleration

The effect of seismic super-shear rupture on the directivity of ground motions using simulated accelerations of a vertical strike-slip fault model is the topic of this study. The discrete wave number/finite element method was adopted to calculate the ground motion in the horizontal layered half space. An analysis of peak ground acceleration （PGA） indicates that similar to the sub-shear situation, directivity also exists in the super-shear situation. However, there are some differences as tbllows： （1） The PGA of the fault-normal component decreases with super-shear velocity, and the areas that were significantly affected by directivity in the PGA field changed from a cone-shaped region in the forward direction in a sub-shear situation to a limited near-fault region in a super-shear situation. （2） The PGA of the fault-parallel and vertical component is not as sensitive as the fault-normal component to the increasing super-shear velocity. （3） The PGA of the fault-normal component is not always greater than the fault-parallel component when the rupture velocity exceeds the shear wave velocity.     

Attenuation characteristics of peak acceleration in North China and comparison with those in the eastern part of North America

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特殊长周期地震动的参数特征研究

近断层脉冲型地震动和远场软土层场地类谐和地震动是两类特殊的长周期地震动,当前的规范均很少对这两类地震作用进行具体的规定。研究了近断层脉冲型和远场类谐和地震动的幅值、幅值比（V／A,D／V）、傅里叶幅值谱和反应谱的差别,分析了相位角和作用循环周期数对简单脉冲的影响,并用于解释两类特殊地震动的工程特征。以集集地震动为数据基础,分析了两类长周期地震动的傅里叶谱和反应谱特征;将平均加速度和位移规准反应谱分别与规范设计谱进行了比较。建议设计谱在长周期段考虑近断层作用和软土场地面波效应的影响。     

Correlation study between ground motion intensity measure parameters and deformation demands for bilinear SDOF systems

The correlation between ground motion intensity measures （IM） and single-degree-of-freedom （SDOF） deformation demands is described in this study. Peak ground acceleration （APG）, peak ground velocity （VPG）, peak ground displacement （DPG）, spectral acceleration at the first-mode period of vibration [As（T1）] and ratio of VPG to APG are used as IM parameters, and the correlation is characterized by correlation coefficients p. The numerical results obtained by nonlinear dynamic analyses have shown good correlation between As（T1） or VPG and deformation demands. Furthermore, the effect of As（T1） and VPG as IM on the dispersion of the mean value of deformation demands is also investigated for SDOF systems with three different periods T=0.3 s, 1.0 s, 3.0 s respectively.     

近断层地震动加速度峰值衰减规律的研究

提出了近断层地面运动的衰减模型,对全球范围内6．0≤Mw≤7．6且震源深度均小于20km的636条地震动加速度峰值进行了统计分析,确定了本文研究的近断层区域为断层距25km,利用此范围内的440条记录进行了近断层加速度衰减规律的研究。水平地震记录分为硬土和软土两种场地类型,竖向地震记录只考虑土层场地,利用最小二乘法进行数据拟合分析,得到PGA随断层距和震源深度变化在不同震级处形成的衰减曲面,分析了近断层处水平、竖向的PGA以及竖向与水平PGA之比(V／H)的衰减规律。     

Ground-motion prediction equations for the intermediate depth Vrancea (Romania) earthquakes

We present the regional ground-motion prediction equations for peak ground acceleration (PGA), peak ground velocity (PGV), pseudo-spectral acceleration (PSA), and seismic intensity (MSK scale) for the Vrancea intermediate depth earthquakes (SE-Carpathians) and territory of Romania. The prediction equations were constructed using the stochastic technique on the basis of the regional Fourier amplitude spectrum (FAS) source scaling and attenuation models and the generalised site amplification functions. Values of considered ground motion parameters are given as the functions of earthquake magnitude, depth and epicentral distance. The developed ground-motion models were tested and calibrated using the available data from the large Vrancea earthquakes. We suggest to use the presented equations for the rapid estimation of seismic effect after strong earthquakes (Shakemap generation) and seismic hazard assessment, both deterministic and probabilistic approaches.     

基于目标反应谱和包线的地震动合成

本文给出了以目标反应谱和目标包线函数为双目标函数的人工地震动合成方法,不仅使人工地震动符合目标反应谱,还在迭代过程中对地震动波形进行调整,使之基本符合目标包线函数,并消除了加速度时程的基线偏移,使速度时程和位移时程更为合理。本文认为当研究非线性结构体系的动力反应规律时,有必要对输入的人工地震动时程的反应谱和包线均进行比较准确的控制,使人工地震动时程符合多个统计特征。     

基于假设检验的地震动强度(烈度)速报方法

地震发生后数分钟内,快速、可靠地判别出地震动强度(烈度)的空间分布,用以估计不同地区的受灾程度,可以为政府开展应急救援并合理分配救援力量提供决策依据,保证救援人员及时、准确地到达极震区并展开搜救,以减少生命财产损失。本文基于统计学中的假设检验方法,对历史震害资料进行统计,提出了一种利用强地震动参数判别地震动强度(烈度)的方法。比较结果表明,本方法所确定的地震动强度(烈度)与实际震害烈度对应较好,能较真实地反映实际震害情况。     

Attenuation characteristics of ground motions in northern China

Four recently developed attenuation models are calibrated by using a very limited amount of strong motion data recorded in China. The research shows that the attenuation characteristics of the earthquake shaking in northern China are similar to those in the western US. The supporting evidence includes Q factors, preliminary results of kappa values, stress drop, shear wave velocity profile in the shallow earth crust, areas enclosed by the isoseismals of Modified Mercalli Intensity V. From these comparisons of different attenuation models, it is recommended that the Crouse and McGuire spectral attenuation model could possibly be used for northern China. Funded by: The Hong Kong Polytechnic University, and partly supported by NSFC (Grant No.59678048)