Seismic site effects by an optimized 2D BE/FE method I. Theory, numerical optimization and application to topographical irregularities     

B. Gatmiri  C. Arson  K.V. Nguyen 《Soil Dynamics and Earthquake Engineering》2008,28(8):632-645

This paper deals with the evaluation of seismic site effects due to the local topographical and geotechnical characteristics. The amplification of surface motions is calculated by a numerical method combining finite elements in the near field and boundary elements in the far field (FEM/BEM). The numerical technique is improved by time truncation. In the first part of this article, the accuracy and the relevance of this optimized method are presented. Moreover, parametric studies are done on slopes, ridges and canyons to characterize topographical site effects. The second part deals with sedimentary valleys. The complexity of the combination of geometrical and sedimentary effects is underlined. Extensive parametrical studies are done to discriminate the topographical and geotechnical effects on seismic ground movement amplifications in two-dimensional irregular configurations. Characteristic coefficients are defined to predict the amplifications of horizontal displacements. The accuracy of this quantitative evaluation technique is tested and discussed.  相似文献   

地震波形数据实时监控软件的实现     

胡星星  滕云田  王喜珍  王晓美  张旸  王晨 《地震地磁观测与研究》2008,29(1):104-108

介绍了地震数据采集器监控软件的设计思路,特别是在实时波形显示上,采用“环形”的显示缓存和“滑动显示窗口”技术,大数据量时也能以左移的方式连续显示实时曲线的动态变化;实时波形的纵坐标范围也是动态变化的,在任何时刻都恰好能在显示区域内完整显示。文章还介绍了如何在显示中消除明显的屏幕闪烁现象,以及对数据从传输到存储、显示的分层设计思想和多线程技术的应用。  相似文献   

Quantitative study on pollen-based reconstructions of vegetation history from central Canada     

《中国科学D辑(英文版)》2008,(8)

Based on high-resolution pollen records from lake cores in central Canada, the present study instructed pollen taxa assignations in ecosystem groups and modern analogue technique, reported major results of quantitative reconstructions of vegetation history during the last 1000 years, and discussed the validation of simulated vegetation. The results showed that in central America (115°-95°W, 40°-60°N), best analogue of the modern vegetation is 81% for boreal forest, 72% for parkland, and 94% for grassland-parkland, which are consistent with vegetation distributions of the North American Ecosystem II. Simulations of the past vegetation from the sedimentary pollen showed climate changes during the past 1000 years: it was warm and dry in the Medieval Warm period, cold and wet in the earlier period and cold and dry in the later period of the Little Ice Age. It became obviously increasing warm and drought in the 20th century. The present studies would provide us scientific basis to understand vegetation and climate changes during the last 1000 years in a characteristic region and in 10-100 year time scales.  相似文献   

非稳定渗流条件下非饱和土边坡稳定分析   总被引：9，自引：2，他引：7  

于玉贞  林鸿州  李荣建  李广信 《岩土力学》2008,29(11):2892-2898

大量的滑坡灾害表明, 水的作用是影响边坡失稳的重要原因,合理地评价边坡的稳定性,需考虑边坡基质吸力场的变化与水的渗流作用。通过稳定与非稳定渗流条件下的非饱和土堤算例,探讨了Bishop和Fredlund非饱和土抗剪强度公式应用于强度折减有限元法的差异,并与极限平衡法的结果进行对比。结果表明,Bishop和Fredlund非饱和土抗剪强度公式的本质是相同的,而从非稳定渗流条件下的分析结果来看,强度折减有限元法分析的安全系数与极限平衡法分析临水坡和背水坡安全系数的最小值相当接近,强度折减有限元法更适合分析边坡的整体稳定性。此外,采用Bishop强度公式可以通过用饱和度代替基质吸力参数来体现基质吸力对强度的影响,在分析饱和度较高的非饱和土边坡稳定性时较为方便。  相似文献   

平衡剖面技术在地震资料解释中的应用   总被引：1，自引：0，他引：1  

周竹生  马翠莲  胡文武  孟葵 《煤田地质与勘探》2008,36(3):67-70

地震资料解释的正确与否直接关系到储层预测的结果与精度,所以平衡剖面解释作为一种辅助手段,对地震解释的多解性起到很好地制约效果,并为其定量化解释研究上开辟了道路。介绍了平衡剖面技术的基本原理和解释机理;以依奇克里油田阿依库木齐剖面为例,阐述了平衡剖面技术在地震解释中的应用效果。结果显示,该剖面构造复原效果较好。并针对平衡剖面技术在地震资料解释中的应用提出了需注意的问题。   相似文献   

野外路线整理过程中的注意事项——RGMAP技术在区域地质调查中的运用     

李永飞  施彬  卞雄飞 《地质与资源》2008,17(3):229-231

野外路线上各要素内容是数字化区域地质填图（RGMAP）工作中最基本信息.在野外数字化信息采集过程中对各要素的描述规范统一是数字化地质成图的重要条件,也是体现数字化区域地质调查特色与效果的最好表现形式.笔者对野外路线整理过程中的实际工作体会进行了总结,意在为初始从事RGMAP技术的同行们提供借鉴.  相似文献   

探地雷达在探测地下采空区范围中的应用   总被引：11，自引：1，他引：10  

刘红军  贾永刚 《地质灾害与环境保护》1999,10(4):73-76,80

由放心弃的地下采空区引起的地面沉陷,已成为一种典型的地质灾害,严重影响工程建设的顺利进行。为了采取相应的治理措施,查明地下采空区的埋深及分布范围显得十分重要通过实例,简述探地雷达在探测地下采空区范围中的应用,探测目的在于确定地下采空区的深度,查明地下采空区的范围,为公路建设选线提供可靠依据。  相似文献   

The porosity and engineering properties of vesicular basalt in Saudi Arabia   总被引：2，自引：0，他引：2  

A. A. Al-Harthi  R. M. Al-Amri  W. M. Shehata 《Engineering Geology》1999,54(3-4):313-320

The presence of non-connected vesicles in extensive basalt flows in western Saudi Arabia greatly affects their engineering properties such as compressive strength, modulus of elasticity, Poisson's ratio and sonic velocities. In order to evaluate some of these properties, the density and/or the porosity of the material must be known. Using conventional methods to determine the porosity or the density of irregular lumps proved to be erroneous. An image analysis technique is suggested to estimate the porosity of the vesicular basalt. The estimated values were correlated against the calculated porosity values using core samples, and were found to have excellent correlation (R=0.99). The estimated porosity values were also correlated against the static and dynamic properties of the basalt and a good level of correlation (R=0.77) was obtained.  相似文献   

新型氢化物发生技术—可移动还原床氢化物发生器：Ⅱ.干扰及其应用     

田肖丹  庄峙厦 《岩矿测试》1999,20(2):87-91

新型的氢化物发生技术－可移动还原床氢化物发生器可以实现微升级样品的测定而不需要对样品进行酸化和使用气－液分离器。应用ＭＲＢＨＧ－电感耦合等离子体发射光谱取得了同等质量的而不同形态的Ａｓ,Ｓｅ的相同信号强度,证明了在ＭＲＢＨＧ体系中氢化物元素之间的干扰得到消除,方法用于合金钢,富硒茶叶等实际样品的测定,标准加入的回收率在９３％－１１４％。  相似文献   

高应变动力试桩法确定桩端土的极限承载力     

郭生浦  刘永翔  杜聿麟 《物探与化探》1999,23(1):51-53

应用高应变动力试桩法确定桩端土的极限承载力是动力触探领域中的一种好方法.运用高应变动力试桩法,可以获得桩在打入过程中的每一锤击下的桩端阻力,即桩端土对桩的端承力.用该力除以桩端的横截面积,即可求得桩端土的极限承载力.结合每一锤的贯入度(或每一锤时桩的入土深度),还可获得桩端土承载力随深度连续变化的测试结果  相似文献