快速有效的转换波共转换点叠加技术   总被引：19，自引：8，他引：19       下载免费PDF全文

许士勇  马在田 《地球物理学报》2002,45(4):557-568

转换波共转换点(Common Conversion Point简称CCP)叠加的关键在于CCP抽道集和非双曲线正常时差校正NMO(Normal MoveOut). 目前方法的精度限制了其在中-浅层或大炮检距情况下的应用. 我们对CCP叠加技术进行了系统研究,导出了新的CCP位置计算公式和非双曲线时距关系式,并给出了具体的CCP抽道集方法. 理论模型试验和实验资料处理表明本文方法精度高、简便易行,特别是对于中-浅层和大炮检距情况也能得到良好的叠加效果.  相似文献   

Influence of the ground profile on the reduction of earthquake motion at the filled man-made islands in the Kobe harbor during the 1995 Hyogoken Nambu earthquake     

Tadahiro Fukusumi  Hitodhi Ozaki  Masao Koba   《Soil Dynamics and Earthquake Engineering》2002,22(9-12):893-899

During the 1995 Hyogoken Nambu earthquake in Kobe, the ground motion at the filled man-made islands in the Kobe harbor was not as severe as that at the mainland. The building damage was also less compared to that on the mainland. It was found by comparative study of earthquake records that the magnitude of acceleration response on the ground surface decreases at the islands as opposed to the mainland. One dimensional effective stress analysis is adopted in this study. Input data has been generated from test results, e.g. the SPT N-value by standard penetration test and shear wave velocity V_s by PS logging. Results obtained by the analyses showed good agreement with the observed records, which is an indication of the suitability of the adopted analysis procedure. From this study, the followings are concluded. By the increase of SPT N-value of the filled layers, liquefaction near ground surface is restrained and damage modes such as ejection of water and soil can be prevented. Since the ground profile at the islands is that considerably soft filled layer and marine clay layers, etc. are present and the thickness of the surface layer is large, the initial natural period of the ground is above 1 s and the natural period is elongated further under the earthquake excitation, which is deemed to be the principal reason for the reduction of the earthquake motion at the ground surface.  相似文献   

小区域热浪风险陛评估方法述评   总被引：2，自引：0，他引：2  

丁晓萍  刘寿东  许遐祯 《内蒙古气象》2010,(1):24-28

文章对国内外热浪和热浪风险性评估的研究成果和方法进行了,综述,最后提出了一种基于层次分析法的小区域热浪风险性评估方法。  相似文献   

乌拉特中旗一次寒潮天气过程分析   总被引：1，自引：0，他引：1  

敖勇 《内蒙古气象》2010,(5):21-22

通过对乌拉特中旗2010年3月13—15日的寒潮天气过程,应用天气学原理和方法进行诊断分析,总结出阻高崩溃型寒潮天气过程形成发展的特点以及预报着眼点。  相似文献   

大气中粘性效应对三维地形波及其波动阻力的影响   总被引：3，自引：0，他引：3  

刘辉志  洪钟祥  桑建国 《气候与环境研究》1999,4(3):315-322

采用两层大气模式, 通过引入瑞利摩擦系数来定性描述大气中粘性机制, 讨论了粘性效应对三维简单地形波及其波动阻力的影响。结果表明,无论低层大气为稳定层结还是不稳定层结, 大气中粘性的存在将减弱地形波的强度, 减小其产生的波动阻力  相似文献   

跨孔电磁波透视法在荷叶塘高架桥岩溶探测中的应用   总被引：2，自引：0，他引：2  

吴有林  陈贻祥  聂士诚 《物探与化探》2009,33(1):102-104

荷叶塘高架桥桥位区岩溶强烈发育。为查明各桥墩位置深部岩溶发育的类型、规模,勘察中采用了跨孔电磁波透视法。结合钻探和跨孔电磁波测试结果对该桥桥墩位置深部岩溶发育的规律进行了分析,对跨孔电磁波测试的验证和效果进行了讨论。钻孔验证表明跨孔电磁波透视法探测精度较高。综合分析表明,可应用跨孔电磁波透视法成果作为确定桩基础持力层的辅助依据。  相似文献   

井间电磁波数值模拟及成像技术   总被引：1，自引：0，他引：1  

杨曦  潘和平 《物探与化探》2009,33(2):140-147

系统地介绍了井间电磁波数值模拟与成像方法的研究现状。正演方面主要讨论了有限差分、有限元和积分方程法,分析了各种方法的优缺点、适用范围,并指出了未来发展趋势;反演方面主要讨论了线性反演和非线性反演,根据井间电磁波成像的性质,对时间域和频率域线性反演方法分别做了详细论述,并给出了未来发展趋势。  相似文献   

软弱夹层速度对瑞利面波频散曲线的影响     

张玉池  温佩琳  张兆京 《矿产与地质》2009,23(4):388-390

文章以弹性波横波速度为参数,利用瑞利面波频散曲线的快速标量传递算法进行正演模拟计算,系统研究软弱层速度对瑞利面波基阶模频散曲线的影响,分析和总结了频率与相速度（f-c）、频率与波数（f-k）、深度与相速度（h—c）等瑞利面波基阶模曲线随软弱层速度变化的规律。  相似文献   

Coastal erosion in response to wave dynamics operative in Sagar Island, Sundarban delta, India     

Barendra Purkait 《Frontiers of Earth Science》2009,3(1):21-33

Coastal erosion at Sagar Island of Sunderban delta, India, has been critically studied. The area is in the subtropical humid region. There are mainly three seasons viz: winter, summer and the monsoon. Different wave dynamic parameters were measured from theodolite observations with leveling staff and measuring gauges during lunar days at two sections of the western and eastern parts of the coastal zone during post-and pre-monsoons. A comparative study was made on the erosion/depositional pattern between the two sections in relation to different hydrodynamic parameters prevailing in these two sections. Plane table mapping was carried out to demarcate the different geomorphic units. The marine coastal landforms show dune ridges with intervening flats bordered by gently sloping beach on one side and a flat beach on the other side. The western part of the beach is mainly sandy; whereas the eastern part is silty and clayey with mud bank remnants. Actual field measurements indicate that the coastal dune belt has retreated to the order by about 20 m since 1985. The eastern part of the beach has lowered by about 2 m since 1985 and the western part was raised almost to the same tune. It is observed that accretion in the western and central parts of the beach took place; whereas severe erosion in the eastern part made the beach very narrow with remnants of mud banks and tree roots. Frequent embankment failures, submergence and flooding, beach erosion and siltation at jetties and navigational channels, cyclones and storm surges made this area increasingly vulnerable.  相似文献   

地层倾角对转换波抽道集的影响     

禹凤林  卢君实 《中国煤炭地质》2009,(4):59-61

共转换点道集的抽取是三维转换波数据处理的重要环节,道集抽取的正确与否受多种因素影响,其中地层倾角的变化能够引起共转换点道集的抽取误差,表现在炮点、检波点的数量与位置的错选。以地层倾向120°,某转换点垂向深度600m,纵横波速度分别为2 500m/s、1 250m/s的单层倾斜模型为例,利用姚陈提出的倾斜界面三维转换波CCP位置计算方法,对地层倾角分别为0°、5°、20°、30°时的炮点、检波点进行统计,确定其对该转换点的贡献情况,结果表明：倾角CCP抽取方法与目前常用的水平界面假设算法计算出的炮点、检波点分布存在很大差异,忽略倾角因素影响将导致不正确的道集叠加,给后期解释带来极大误差。  相似文献