会泽黄草岭磷矿地质特征及成矿浅析     

丁小平  牛泽林  杨义明 《云南地质》2014,(2):201-206

会泽县黄草岭磷矿含矿层位为下寒武统渔户村组中谊村段（∈1yz）,胶磷矿由砂屑、砾屑、鲕粒组成,孔隙一基底胶结,多伴铁泥质胶结,颗粒形态次圆、不规则状,细、粗颗粒含量不均;沉积环境处于古陆边缘浅海地域,矿物质来源主要取决于古陆风化淋滤作用.  相似文献   

厚软覆盖层场地地震反应分析方法研究     

王笃国  赵成刚 《工程地质学报》2014,22(6):1128-1134

遭遇地震动作用时,厚软覆盖层场地由于其剪切模量低,极易产生较大的剪应变,采用等效线性化方法进行土层反应分析计算得到的响应高频成分被低估,峰值加速度偏低,对于工程抗震设防偏于不安全。本文给出了基于移动平均线和Parzen谱窗的频率相关等效线性化方法,并和有实际强震记录的厚软场地进行了对比分析,结果表明本文方法比等效线性化方法能更有效地模拟地震波在厚软覆盖层场地中的传播规律。最后采用本文方法和等效线性化方法对天津滨海新区某一典型厚软场地进行了地震反应计算,并对计算结果进行了对比分析。  相似文献   

About the Symmetry of the Upscaled Equivalent Transmissivity Tensor   总被引：1，自引：0，他引：1  

Mauro Giudici  Chiara Vassena 《Mathematical Geology》2007,39(4):399-408

This paper provides a proof of the symmetry of the equivalent transmissivity tensor computed with a method based on the solution of the balance equation at the fine scale with integrated finite differences. The basic hypotheses are that the balance equation is solved on a block assigning Dirichlet boundary conditions that vary linearly with the space coordinates and the equivalent transmissivity tensor is computed as the linear tensor relating average flux and hydraulic gradient.  相似文献   

利用地面控制点进行卫星摄影三线阵CCD相机的动态检测   总被引：5，自引：0，他引：5  

王任享  王建荣  赵斐  刘薇 《地球科学与环境学报》2006,28(2):1-5

卫星发射及在轨飞行中,环境变化会影响三线阵CCD相机的内方位元素。实际上使相机成为不符合摄影测量定义的相机,导致由经典摄影测量原理推导的有关公式应用受到影响。因此,将变化了的内方位元素规范为正视相机的x坐标为零的内方位元素系统,而此系统的其他参数则作为EFP法反解内方位元素的待求参数,并给出了计算数学模型及模拟计算结果。  相似文献   

结构附加粘滞阻尼器的抗震设计   总被引：2，自引：0，他引：2  

李波  梁兴文 《震灾防御技术》2007,2(1):1-10

本文结合抗震设计规范反应谱,给出了一个附加非线性流体粘滞阻尼器结构的抗震设计方法。研究了非线性阻尼器的力学特性,引入了非线性流体阻尼器的等效线性阻尼比,给出了计算最大加速度时刻附加非线性流体阻尼器结构反应的荷载组合系数,提出了按阻尼力的水平力分量与楼层剪力成正比的原则分配阻尼器阻尼系数的方法。同时给出了基于抗震规范设计反应谱附加非线性阻尼器结构的设计流程,通过一个算例说明了使用该方法设计附加非线性粘滞阻尼器结构的全过程。算例分析表明,这种设计方法适合于手算,便于设计人员掌握,在初步设计阶段可以快速、有效地设计满足给定性能水平的附加非线性流体阻尼器体系。  相似文献   

一种改进的全局优化算法及其在面波频散曲线反演中的应用   总被引：19，自引：5，他引：14       下载免费PDF全文

崔建文 《地球物理学报》2004,47(3):521-527

建议一种SA和GA相结合的策略,较好地解决了GA收敛早熟及SA搜索效率较低的问题,提高了全局优化计算效率;在应用其依据面波频散曲线反演工程场地剪切波速时,利用简化剥层法提供较小的模型空间,取得了较好的反演效果.  相似文献   

Evaluation of cyclic shear strength of mixtures with sand and different types of fines     

Uk-Gie Kim  Li Zhuang  Dongwook Kim 《Marine Georesources & Geotechnology》2017,35(4):447-455

Soils are classified as sandy soils and clayey soils in most soil classification systems, and appropriate equations are used for practical design, depending on soil type, to represent each soil behavior. Sand-clay mixtures, however, need a special standard to evaluate their specific behaviors since they are categorized as intermediate soils or transitional soils and typically show intermediate properties. In this article, a series of cyclic triaxial tests were conducted on specific sand-fines mixtures with three fine types and various fine contents. The behaviors of various soil mixtures (silica sand with Iwakuni natural clay, Tottori silt, and Kaolin clay) were investigated by considering a concept of granular void ratio expressed in terms of sand structure. The cyclic shear strengths of the soil mixtures were also evaluated by increasing the fine content but no more than the threshold fine content. In the results, the cyclic deviator stress ratio decreased in dense soils whereas it increased in loose soils by increasing the fine content. In addition, a simple equation was proposed to predict the liquefaction resistance of sandy soils by evaluating the cyclic deviator stress ratio with a concept of equivalent granular void ratio.  相似文献   

位场延拓的积分-迭代法   总被引：22，自引：14，他引：22       下载免费PDF全文

徐世浙 《地球物理学报》2006,49(4):1176-1182

本文介绍一种新的位场延拓方法——积分-迭代法.将起伏面上的实测位场值，垂直投影至起伏面下部的一个水平面上，作为该水平面上的位场初始值.根据该水平面上的初始值，用积分方法计算起伏面上的位场值.用起伏面上的实测值与计算值的差值，对水平面上的位场值进行校正.如此反复迭代，直至起伏面上的实测值与计算值的差值小到可以忽略.有了水平面上的位场值后，就可以用积分的方法或其他方法计算水平面以上的任意曲面或水平面的位场值.该方法原理简单，不用解线性代数方程组，有较高的计算速度.它特别适用于位场向下延拓，有良好的延拓效果.本文还介绍了积分迭代法的应用实例.  相似文献   

The importance of crustal structure in explaining the observed uncertainties in ground motion estimation     

John Douglas  Hideo Aochi  Peter Suhadolc  Giovanni Costa 《Bulletin of Earthquake Engineering》2007,5(1):17-26

In this short article, the possible reduction in the standard deviation of empirical ground motion estimation equations through the modelling of the effect of crustal structure is assessed through the use of ground-motion simulations. Simulations are computed for different source-to-site distances, focal depths, focal mechanisms and for crustal models of the Pyrenees, the western Alps and the upper Rhine Graben. Through the method of equivalent hypocentral distance introduced by Douglas et al. [(2004) Bull Earthquake Eng 2(1): 75–99] to model the effect of crustal structure in empirical equations, the scatter associated with such equations derived using these simulated data could be reduced to zero if real-to-equivalent hypocentral distance mapping functions were derived for every combination of mechanism, depth and crustal structure present in the simulated dataset. This is, obviously, impractical. The relative importance of each parameter in affecting the decay of ground motions is assessed here. It is found that variation in focal depth is generally more important than the effect of crustal structure when deriving the real-to-equivalent hypocentral distance mapping functions. In addition, mechanism and magnitude do not have an important impact on the decay rate.  相似文献   

倒虹吸混凝土管道的地震反应分析          下载免费PDF全文

徐平  唐献富  夏唐代 《地震工程学报》2007,29(4):352-356

基于土体的等效粘弹性模型,结合场地典型剖面的土体特性以及室内实验确定的各力学参数,采用时域积分和迭代的方法研究了沁河倒虹吸管道在地震作用下的反应,分析了管道截面中间底部点绝对地震位移、顶部点相对于底部点的地震动位移及管道动静综合主应力的变化规律;并根据有限元时程法的分析结果,按照混凝土承载能力极限状态设计式,对管身混凝土的抗拉、抗压安全度进行校核。结果表明,在人工地震波、调整后的E1 Centro和Pulgas地震波分别输入的情况下沁河渠道倒虹吸管道均满足抗震要求。  相似文献