关于电荷面分布问题的讨论

本文研究了电荷面分布时“面模型”建立的可行性、任意带电面两边场强改变量和电荷面分布时所受电场力的大小.     

气象奇点与云南最大震级预报研究

根据地震活动与气象要素之间的密切关系,采用大量气象资料选取预报因子,将气象统计理论应用于地震预报,开创了地震预报的数值预报新方法,并对中国云南5个地震分区,分上下半年做出了最大震级预报,其置信度达到特别显著水平。这对提高地震预报水平将具有深远意义。     

红石河堰塞湖漫顶溃坝风险评估

四川省青川县红石河堰塞湖是2008年5月12日汶川大地震形成的34座大型堰塞湖之一,是由东河口滑坡堵塞红石河形成的。该堰塞体高度约50 m、宽度约250 m、顺河向长度约500 m、形成的最大库容约400万m3。本文作者对红石河堰塞体做了较详尽的现场试验,包括土的冲蚀试验、土的基本物性试验等。基于现场试验数据,对土的冲蚀性和漫顶溃坝风险做了详细的分析。结果显示,从土的抗冲蚀性角度考虑,只要有水溢出就会有土体被冲蚀,这说明红石河堰塞体的漫顶溃决可能性较高。本文还提出经验公式来预测红石河堰塞体漫顶的溃决时间,大约为4.5d,如果考虑到大石块对抗冲蚀稳定性的有利影响,这一数值会增大。此外,还研究了溃决深度随时间的变化规律。     

Fault Slip Model of 2013 Lushan Earthquake Retrieved Based on GPS Coseismic Displacements

Lushan Earthquake (~Mw 6.6) occurred in Sichuan Province of China on 20 April 2013, was the largest earthquake in Longmenshan fault belt since 2008 Wenchuan Earthquake. To better understand its rupture...     

Research of air-cushion isolation effects on high arch dam reservoir

A three-dimensional (3D) finite element model of air-cushion isolated arch dam is presented with the nonlinear gas-liquid-solid multi-field dynamic coupling effect taken into account.In this model,the displacement formulation in Lagrange method,pressure formulation in Euler method,nonlinear contact model based on Coulomb friction law are applied to the air-cushion,reservoir and contraction joint domain,respectively.The dynamic response of Jinping I arch dam with a height of 305 m is analyzed using the seismic records of the Wenchuan Earthquake in 2008.Numerical results show that the air-cushion isolation reduces significantly the hydrodynamic pressure as well as the opening width for the contraction joints of high arch dam.     

An estimate of maximum ground surface motion for non zero surface velocityEstimation du mouvement sismique maximal à la surface du sol pour une celerite d'ondes non nulle en surface

The increasing need for probability seismic hazard assessment (PSHA) of critical facilities sometimes leads to unrealistic earthquake scenarios with very high induced ground motions. From a physical standpoint these high motions cannot exist because of the limiting resistance capacity of the soil strata through which the seismic waves travel. A simple analytical model is proposed to bound the maximum ground surface acceleration that any soil deposit can transfer. This model is an extension to non zero ground surface velocity of a previously presented model. To cite this article: A. Pecker, C. R. Mecanique 332 (2004).     

地震液化效应的综合评价

土的地震液化具有地基失效和隔振双重效应。本文在分析了这两种效应的基础上,提出了一种综合评价方法。     

概率地震危险性评价系统开发

工程建设时必须对工程场地的地震危险性进行评价,并且对工程结构物要采取抗震设计。由于相关部门往往针对某一地区只提供一个地震设防加速度范围值或地震设防烈度值,而且某一地震烈度值所对应的加速度值的范围也很大,使得在实际应用中给具体工程安全、经济地选用合适的抗震设防加速度带来一定困难;为解决这个问题,本文以概率地震危险性评价理论为基础,开发了一套地震危险性评价系统。利用该评价系统根据相关地震活动性参数,可以方便、快速地计算出具体工程应该采用的抗震设防加速度值,从而解决了工程活动中安全、经济地选用抗震设防加速度值的问题。文中还针对潜在线源和潜在面源的处理难以在程序上实现这一难题,分别提出了一种精确求解和近似求解的算法。本文并以实例进行了评价计算,计算结果与中国地震局公布的数据符合较好,从而验证了开发的评价系统具有较好的可信度。     

An estimate of maximum ground surface motionEstimation du mouvement sismique maximal à la surface du sol

The increasing need for probability seismic hazard assessment (PSHA) of critical facilities sometimes leads to unrealistic earthquake scenarios with very high induced ground motions. From a physical standpoint these high motions cannot exist because of the limiting resistance capacity of the soil strata through which the seismic waves travel. A simple analytical model is proposed to estimate a bound to the maximum ground surface acceleration that any soil deposit can transfer. To cite this article: A. Pecker, C. R. Mecanique 331 (2003).     

Fragility analysis of bridges under ground motion with spatial variation

Seismic ground motion can vary significantly over distances comparable to the length of a majority of highway bridges on multiple supports. This paper presents results of fragility analysis of highway bridges under ground motion with spatial variation. Ground motion time histories are artificially generated with different amplitudes, phases, as well as frequency contents at different support locations. Monte Carlo simulation is performed to study dynamic responses of an example multi-span bridge under these ground motions. The effect of spatial variation on the seismic response is systematically examined and the resulting fragility curves are compared with those under identical support ground motion. This study shows that ductility demands for the bridge columns can be underestimated if the bridge is analyzed using identical support ground motions rather than differential support ground motions. Fragility curves are developed as functions of different measures of ground motion intensity including peak ground acceleration, peak ground velocity, spectral acceleration, spectral velocity and spectral intensity. This study represents a first attempt to develop fragility curves under spatially varying ground motion and provides information useful for improvement of the current seismic design codes so as to account for the effects of spatial variation in the seismic design of long-span bridges.