川滇分区地震烈度衰减特征研究   总被引：2，自引：1，他引：1  

董曼  程佳  魏文薪  陈通 《震灾防御技术》2015,10(S1):760-769

考虑到不同区域地震烈度衰减规律的差异性,本文通过分析川滇地区地震空间分布、震害及烈度分布特征,搜集并整理了1900年以来川滇地区的140个5级以上地震案例,利用联合椭圆衰减模型,结合川滇地区的地质构造特征,建立了川滇分区地震烈度衰减关系。对比结果表明：不同区域的地震烈度衰减存在显著差异,尤其是在M=5和M=7级时区域差别明显;同时,与已有成果的对比结果也可看出,滇西地区在M=7级时近场烈度明显偏低,而川西北及滇中地区在M=5级时虽与中国西部地区基本一致,但也均低于其它分区。上述结果对川滇地区地震灾害快速评估和地震应急具有重要参考价值。  相似文献   

Stick-slip behavior of Indian gabbro as studied using a NIED large-scale biaxial friction apparatus     

Tetsuhiro Togo  Toshihiko Shimamoto  Futoshi Yamashita  Eiichi Fukuyama  Kazuo Mizoguchi  Yumi Urata 《地震科学（英文版）》2015,28(2):97-118

This paper reports stick-slip behaviors of Indian gabbro as studied using a new large-scale biaxial friction apparatus, built in the National Research Institute for Earth Science and Disaster Prevention (NIED), Tsukuba, Japan. The apparatus consists of the existing shaking table as the shear-loading device up to 3, 600 kN, the main frame for holding two large rectangular prismatic specimens with a sliding area of 0.75 m² and for applying normal stresses σ_n up to 1.33 MPa, and a reaction force unit holding the stationary specimen to the ground. The shaking table can produce loading rates v up to 1.0 m/s, accelerations up to 9.4 m/s², and displacements d up to 0.44 m, using four servocontrolled actuators. We report results from eight preliminary experiments conducted with room humidity on the same gabbro specimens at v = 0.1-100 mm/s and σ_n = 0.66-1.33 MPa, and with d of about 0.39 m. The peak and steady-state friction coefficients were about 0.8 and 0.6, respectively, consistent with the Byerlee friction. The axial force drop or shear stress drop during an abrupt slip is linearly proportional to the amount of displacement, and the slope of this relationship determines the stiffness of the apparatus as 1.15×10⁸ N/m or 153 MPa/m for the specimens we used. This low stiffness makes fault motion very unstable and the overshooting of shear stress to a negative value was recognized in some violent stick-slip events. An abrupt slip occurred in a constant rise time of 16-18 ms despite wide variation of the stress drop, and an average velocity during an abrupt slip is linearly proportional to the stress drop. The use of a large-scale shaking table has a great potential in increasing the slip rate and total displacement in biaxial friction experiments with large specimens.  相似文献   

2004-2007年江西雷电分布特征分析   总被引：2，自引：2，他引：0  

李玉塔  傅智斌 《气象与减灾研究》2008,31(2):70-72

基于2004--2007年江西省地闪监测资料,分析江西雷电分布特征。统计表明,江西大部分县（市）年平均地闪5000～15000次。从时间分布看,江西雷电全年都有发生,主要出现在4—9月,其中6—8月最为活跃,1d中地闪主要发生在12—20时。从空间分布看,年平均地闪10000～15000次的高密集区主要分布在吉安、赣州、宜春、南昌、上饶和鹰潭等地。从雷电流的特性看,负闪居多,年正、负闪数之比为0．0202-0．0431。从雷电流强度上看,地闪雷电流强度绝对值主要为2～20kA,其中正闪主要为3—55kA,负闪主要为-3－-16kA,正闪平均强度是负闪的2．95倍。  相似文献   

利用雷达回波特征和地面资料确定0312号台风"科罗旺"强度     

刘丽君 《气象研究与应用》2003,24(4):24-27

通过分析0312号台风"科罗旺"过程的雷达回波特征和地面资料,应用"热带气旋强度综合判据表"的办法,确定该台风的强度,并分析其大风分布的特点.为将来雷达探测台风业务,分析回波资料积累一些经验和方法,从而能更好的利用雷达回波应用于台风预报业务.  相似文献   

Derivation of design soil coefficients (S) and response spectral shapes for Eurocode 8 using the European Strong-Motion Database   总被引：1，自引：0，他引：1  

Julien Rey  Ezio Faccioli  Julian J. Bommer 《Journal of Seismology》2002,6(4):547-555

A revision is presently under way to upgrade the status of the `Designrecommendations for earthquake resistance of structures', commonlyreferred to as Eurocode 8 (or EC8). In order to improve the definition ofthe design elastic response spectra (ERS) as defined in the Eurocode 8 –Part 1 (Draft May 2001), the values of the soil amplification factors havebeen calculated for sites on sedimentary soils, both stiff (category B) andsoft (category C), with respect to rock sites (category A), such ascontemplated in EC8. The work was performed by a systematic study ofresponse spectra as a function of magnitude and site conditions, usingrecords from the European Strong-Motion Database.The results confirm the occurrence of systematic spectral amplification onsedimentary soils with respect to reference rock in a large set of Europeanstrong motion data. Such amplification has been quantified through ameasure derived from the Housner Spectrum Intensity definition.The values of the soil coefficients recommended in the current version ofEC 8 are shown to be realistic for category C, in the case of a moderateseismicity context. However the values for subsoil class B need to besignificantly increased both for the moderate and high seismicity context.  相似文献   

守恒系统中台风强度变化及其可能因子的数值研究     

罗哲贤 《气象学报》2003,61(3):302-311

用一个高分辨率的 f平面正压涡度方程模式 ,实施了时间积分为 36h的 2 1组试验 ,研究相邻中尺度涡旋与台风涡旋的相互作用。结果指出 :这种相互作用能否导致台风加强 ,取决于两类因子 :一是台风涡旋最大风速的取值以及圆形基流切变的强弱 ;二是切变基流中的中尺度涡旋的自身条件 ,包括中尺度涡旋的分布、尺度、强度和结构。台风强度与初始中尺度涡旋的尺度、强度之间存在着非线性的联系  相似文献   

A new simple method to substantially increase the seismic stability of reinforced soil structures   总被引：1，自引：0，他引：1  

M. Shinoda  T. Uchimura  F. Tatsuoka  M. Tateyama  T. Natsuki 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1115-1123

A preloading and prestressing (PLPS) method has been proposed to substantially decrease the transient and residual vertical compression of geosynthetic-reinforced soil (GRS) structures subjected to long-term traffic load. It is shown that by using a newly developed device (called the ratchet system) in addition to the PLPS procedure, the seismic stability of PLPS GRS structures becomes very high. The ratchet system can not only maintain high prestress when the backfill tends to contract but also prevent the expansion of the backfill, both effectively restraining the shear and bending deformation of the structure subjected to seismic load.  相似文献   

1739年银川-平罗8级地震灾害的历史辨析   总被引：1，自引：0，他引：1  

白铭学  焦德成 《地震工程学报》2005,27(2)

在查阅了大量有关1739年银川-平罗8级大震历史资料的基础上,结合建国以来对银川平原地震的研究成果,研究了1739年银川-平罗8级地震的地震烈度分布及其灾害特点。研究认为:该地震的发震构造为贺兰山东麓断裂,而极震区位于其东南的银川-平罗一带,与银川地堑第四纪沉降中心相吻合,这主要是受到工程地质条件的影响。其震害特点对减轻未来地震灾害、城市规划等都有参考价值。  相似文献   

山西地震基本烈度特点分析     

兰青龙  苏宗正 《山西地震》1995,(2):9-13

本文从地震基本烈度含义的演变入手，重点叙述了山西地震基本烈度的分布特征、影响场、地震烈度区划图的正确使用和建设场地的地震安全性评价关系等问题。  相似文献   

吉林台电站场地地震活动性分析     

柔洁 《内陆地震》1989,3(1):34-41

本文利用目前较新的方法对吉林台电站坝区地震活动性进行了多方面的探讨。资料分析与处理‘包括绘图均在计算机上进行。  相似文献