地质特征轨迹的出露概率研究     

周小文 《岩土力学》2004,25(Z2):89-92

将地质特征的发展轨迹视为Brown运动.基于Brown运动理论,在裂隙穿越矩形区域概率公式的基础上,推导了单条裂隙轨迹和多条裂隙轨迹穿越任意区域的概率公式,并用算例进行了演算,从结果可知,如果通过一些实际工程的考察,确定出合理的轨迹运动参数,则用Brown运动有可能较好地模拟岩体裂隙(或其它地质特征轨迹)的运动规律.利用得到的概率公式,研究了矩形区域(边长为a,b)内裂隙的穿越概率与归一化距离b/a之间的关系.结果表明,如果地质特征轨迹符合Brown运动,则在0≤b/a≤1范围内,穿越概率随b/a的增加急剧降低;当b/a>1时,随着b/a的增加,概率减小比较缓慢.  相似文献   

A Global Vertical Reference Frame Based on Four Regional Vertical Datums   总被引：1，自引：0，他引：1  

Burša  M.  Kenyon  S.  Kouba  J.  Šíma  Z.  Vatrt  V.  Vojtíšková  M. 《Studia Geophysica et Geodaetica》2004,48(3):493-502

A Global Vertical Reference Frame (GVRF) has been realized by means of several regional and local vertical datums (LVD) distributed world-wide: the North American Vertical Datum 1988 (NAVD 88), Australian Height Datum 1971 (AHD 71), LVD France, Institute Géographique National 1969 (IGN 69) and Brazilian Height Datum 1957 (BHD 57). The vertical shifts of the above LVD origins have been related to the adopted reference geopotential value W ₀ = (62 636 856.0 ± 0.5) m²s^–2 and they were determined at the 5 cm level. However, the W ₀ reference value can be chosen arbitrarily, the methodology, which was developed here, does not require that the above value be adopted.  相似文献   

Comparing the adequacy of alternative ground motion intensity measures for the estimation of structural responses     

Paolo Giovenale  C. Allin Cornell  Luis Esteva 《地震工程与结构动力学》2004,33(8):951-979

Practical methods for the probability‐based seismic assessment of structures make use of estimates of demands produced by earthquakes of different intensities. The uncertainties associated with these estimates are highly dependent on the variable adopted as the intensity measure (IM, e.g., PGA, spectral acceleration, etc.). This generates the need to compare the efficiency of an originally adopted IMwith that of a new candidate. This implies comparing the dispersion of the demand measure (DM, e.g., maximum interstorey drift ratio, ductility demand, etc.) conditional to each of the two IMs. In order to obtain the demand estimates in a conventional way, a full set of dynamic response analyses should be performed for each IM under scrutiny, i.e., multiple records scaled at several fixed values of each IM. The procedure developed here serves to accelerate this comparison avoiding the effort required to evaluate the dynamic responses of the structure for all the ground motion time histories considered every time that a new IM is adopted. For this purpose, use is made of available results of analyses performed for a different (i.e., the original) IM. Two methods are proposed: the direct method involves performing a regression of the results obtained from the original analyses, taking the candidate IM as the independent variable. The indirect method involves rebuilding the probability density function of the DM given a defined value of the candidate IM by means of the total probability theorem, using the results of the original analyses and certain data relating the two IMs. The proposed methods have been tested by application to several SDOF systems with different periods and different cyclic‐response backbone curves. The conditions affecting their approximation are explored, and some criteria to improve them are identified. The procedure can also be used to determine the optimum value of a parameter to be used in a parameter‐based IM. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Simulation of the seismic performance of the Bolu Viaduct subjected to near‐fault ground motions     

S. W. Park  H. Ghasemi  J. Shen  P. G. Somerville  W. P. Yen  M. Yashinsky 《地震工程与结构动力学》2004,33(13):1249-1270

The seismic performance of the Bolu Viaduct in the Duzce, Turkey, earthquake of November 1999 was studied via a non‐linear, time‐history analysis of a multi‐degree of freedom model. The viaduct had a seismic isolation system consisting of yielding‐steel energy dissipation units and sliding pot bearings. The Duzce earthquake caused a surface rupture across the viaduct, which resulted in excessive superstructure movement and widespread failure of the seismic isolation system. The effect of the rupture was modeled by a static, differential ground displacement in the fault‐parallel direction across the rupture. The ground motions used in the analysis contain common near‐fault features including a directivity pulse in the fault‐normal direction and a fling step in the fault‐parallel direction. The analysis used a finite element package capable of modeling the mechanical behavior of the seismic isolation system and focused on the structural response of a 10‐span module of the viaduct. This analysis showed that the displacement of the superstructure relative to the piers exceeded the capacity of the bearings at an early stage of the earthquake, causing damage to the bearings as well as to the energy dissipation units. The analysis also indicated that shear keys, both longitudinal and transverse, played a critical role in preventing collapse of the deck spans. Published in 2004 by John Wiley & Sons, Ltd.  相似文献   

A study on characteristics of tectonic block motion and tectonic setting of strong earthquakes in northern part of the Shanxi fault depression zone     

于慎谔 《地震学报(英文版)》2004,17(4):417-425

Introduction Shanxi fault depression zone (SFDZ) is one of important Cenozoic fault basin zones and strong earthquake belts in Chinese mainland. Its northern part has aroused wide research interests due to the complicated tectonics and high activity of strong earthquakes there. Early researches on this depression zone were carried out since 60s of last century (DENG, et al, 1973; DENG, YOU, 1985; LU, DING, 1985; XU, 1990; XU, et al, 1996, 2002). In 90s of last century, the geologica…  相似文献   

A series solution for surface motion ampli-fication due to underground group cavities: Incident P waves     

梁建文  张浩  Vincent W Lee 《地震学报(英文版)》2004,17(3):296-307

Introduction In recent years some big cities in China commonly build subways in central urban areas to improve crowded surface transportation, and the subways usually are large-scale group cavities composed by two parallel cavities. Construction of large-scale group cavities will certainly affect the design ground motion near the cavities, and further affect seismic safety of the existing build-ings nearby. So it is of significance to estimate this effect on seismic design of the buildings. H…  相似文献   

The GIS and analysis of earthquake damage distribution of the 1303 Hongtong M=8 earthquake     

高孟潭  金学申  安卫平  吕晓健 《地震学报(英文版)》2004,17(4)

Introduction The 1303 Hongtong earthquake is an important earthquake in the eastern China. There is a lot of information in historical documents about the earthquake and many traces destroyed by the earthquake in the southern Shanxi Province. Many scholars have studied the earthquake from dif-ferent aspects, but mainly limited the definitions of the isoseismal and three factors of the earth-quake. Owing to being limited by the analysis technique, many useful damage information of the earthqu…  相似文献   

Prediction analysis of long-term memory effect for calamity gray series     

CHEN Zhaonan 《中国科学D辑(英文版)》2004,47(3)

Are human able to foresee the future? For thou-sands of years close attention has been paid to this issue. At the present day, in order to survive from competition and to predominate over the nature, hu-man抯 desire of forecasting things has become more and more intense. Compared to conquering space, more people yearn for being able to control the time. From ancient to the present, mankind always dream of contacting the past, governing the present and tran-scending the future. Recent years in…  相似文献   

软土覆盖层地震面波的地震动反应及台湾8级地震对上海高层建筑影响的估计          下载免费PDF全文

徐永林 《地震工程学报》2004,26(4):309-314

用2002年3月31日台湾Ms7．5地震时上海地区软土地表和基岩记录的加速度资料讨论了地表软土覆盖层面波的地震动反应，并用经验格林函数法合成了台湾未来8级大地震在上海基岩和土层处的面波加速度时程，初步估计了其对高层建筑的影响。其结果对上海的工程抗震设计有参考价值。  相似文献   

三危山断层近场地震动对敦煌莫高窟的影响研究          下载免费PDF全文

卢育霞  石玉成 《地震工程学报》2004,26(3):260-264

三危山断层距敦煌莫高窟仅约3km。本建立横向均匀成层的地震断层模型，利用随机有限断层方法，预测三危山断层发生5．5级、6．0级、6．5级地震时地震动对莫高窟的影响。研究表明逆断层使三危山断层辐射的地震动分布形态呈现出明显的上下盘效应。同时，将计算PGA值与已有的根据其它地区地震记录推出的PGA衰减关系进行了对比分析，认为该结果可供莫高窟抗震防护加固设计时参考。  相似文献