路堑边坡平面滑动演化过程及远程滑动机制的模拟与分析     

王浩  孙木子  马新凯  廖小平  林一夫  吴志刚 《工程地质学报》2015,23(3):438-447

永宁高速公路K117滑坡路段原为在泥质粉砂岩单斜地层内开挖2级形成的路堑边坡,开挖后产生典型平面滑动,在中部滑床形成长约25m的滑动槽,产生最远达35m的远程滑距,其成因机制复杂。本文在对滑坡基本特征及孕育过程开展详细调查研究的基础上,采用节理有限单元法对该滑坡经路堑开挖导致高位坍滑、刷方变更后触发高速远程滑塌、滑塌后壁残留滑体牵引松动,以及对其实施卸载、支挡回填及锚固的治理过程开展数值模拟,再现了该滑坡孕育发展全过程及其稳定性演化规律;分析了该边坡破坏的平面滑动机构及滑动面的物理力学特征,论述了该类滑坡启动高速远程滑动的开挖松弛致滑机理和裂隙充水致滑机理,最后提出了预测及治理该类滑坡的6点建议。研究表明,在单斜地层开挖路堑,使顺倾向软弱结构面临空暴露时,可能诱发边坡整体卸荷松弛,产生较大的不平衡滑坡推力,而卸荷松动产生的张裂隙导致滑坡对降雨入渗十分敏感,不平衡力和裂隙水压力的共同作用可迅速剪断滑面,伴随势能向动能的转化,产生高速远程滑动。  相似文献   

Wave reflection characteristics of plane, dentated and serrated seawalls     

S. Neelamani  N. Sandhya 《Ocean Engineering》2003,30(12):1507-1533

The hydrodynamic performance of vertical and sloped plane, dentated and serrated seawalls were investigated using physical model studies. Regular and random waves of wide range of heights and periods were used. Tests were carried out for different inclinations of the seawall (i.e. θ=30, 40, 50, 60 and 90°) and for a constant water depth of 0.7 m. The wave reflection was measured to assess the dissipation character of the seawalls. It was observed that the serrated seawall was superior to the plane and dentated seawall in reducing the wave reflection. Even for the vertical case, the coefficient of reflection due to regular waves for dentated seawall ranged from 0.6–0.99 and for the vertical serrated seawall it was 0.45–0.98, whereas for the vertical plane wall, it was almost 1.0. It was found that the characteristic dimension of the seawall (i.e. L/W) and the relative water depth (i.e. d/L) were better influencing parameters compared to the conventionally used surf similarity parameter ‘ξ’ (ξ=tan θ/(H_i/L)^0.5) in predicting the reflection from the dentated and serrated seawall, where L is the local wave length, W the width of the dent along the length of the seawall slope, d the water depth at the toe and H_i is the incident wave height. A similar trend was observed for the random waves too. The reduction in the wave reflection due to random waves for the dentated seawall as compared to the plane seawall was about 18% and for the serrated seawall, it was 20%. It was observed that the reflection due to random waves was lesser for all the three different walls than the regular waves, due to the mutual interaction of random waves. Multiple regression analysis on the measured data points was carried out and predictive equations for the reflection coefficient were obtained for both regular and random waves. This study will be useful in the design of energy dissipating type vertical quay walls in ports and harbours, sloped seawalls for shore protection from erosion and sloped caisson as breakwaters. Comparison of predictive formulae with the experimental results revealed that the prediction methods were good enough for practical purposes.  相似文献   

Evaluation of a 256×256 Si:As IBC detector array for astronomy     

M. E. McKelvey  Robert E. McMurray Jr.  C. R. Mccreight  W. J. Forrest  J. D. Garnett  N. Lum  J. Asbrock  R. White  R. Kelchner  L. Lum  L. Pham 《Experimental Astronomy》1994,3(1-4):167-168

256×256-element IBC Si:As arrays have been evaluated for applications in IR astronomy from space-borne platforms. Basic figures of merit were measured at IR flux levels simulating those expected in space-based astronomical observations. Results include dark current <20e ^-/s, G as high as 3.8, / of 20%, and read noise below 100 rms e^-.  相似文献   

水平角观测时竖轴倾斜引起误差的改正方法探讨     

胡特彧  杨松林  田爱军 《北京测绘》2008,(2):43-46

对于水平角观测时垂直轴倾斜带来的影响,一是采用测回间重新整平的方法来削弱;二是在有竖盘指标水准管的情况下,读取格值施加改正数的方法来削弱。但这两种方法的精度有限,且对于无竖盘指标水准管的仪器目前没有提出相应的解决方法,＂虚拟目标法＂可以有效地解决这个问题。  相似文献   

浅析像素工厂(PF)生产DOM的平面精度     

石善球  蒋淼  黄亚萍 《现代测绘》2008,31(4)

像素工厂是一套全新的影像处理系统,本文介绍通过像素工厂和全数字摄影测量工作站生产同一地区DOM,并对两套系统生产的产品进行精度检测,得出精度报告。  相似文献   

半空间饱和介质内圆形洞室对平面P1波的散射   总被引：1，自引：0，他引：1       下载免费PDF全文

徐平  铁瑛  夏唐代 《地震工程学报》2008,30(4):369-375

考虑土颗粒和孔隙流体的压缩性以及孔隙流体与土骨架之间的粘性耦合作用,采用修正的Biot模型,假定半空间表面不透水,得到了平面P1波(快压缩波)在半空间表面的反射P1波、P2波(慢压缩波)和SV波(剪切波)的幅值.采用大圆弧假定将半空间内圆形洞室的散射问题转化为大圆弧和圆形洞室的多重散射问题,运用波函数展开法将入射波、反射波以及半空间表面和洞室的散射波的势函数展开成Fourier-Bessel函数的无穷级数形式,由Graf加法定理得到同一坐标系下的势函数的表达式,根据半空间表面和洞室完全自由的边界条件得到了待定复系数的理论解.通过数值计算,着重分析了平面P1波垂直向上入射时无量纲入射频率和洞室埋藏深度等对洞室的动应力集中因子和半空间表面的归一化水平和竖向位移的影响.  相似文献   

华北平原地区夏季严重旱涝特征诊断分析   总被引：48，自引：0，他引：48  

孙安健  高波 《大气科学》2000,24(3):393-402

利用华北平原地区13个站1951～1995年6～8月的降水量资料讨论了该地区发生的严重旱涝特征,发现各有7年出现严重干旱和雨涝。严重干旱主要发生在6、7月份,严重雨涝主要发生在7、8月份。特大旱涝发生最频繁的地带在燕山南麓和太行山东麓。50年代多雨涝,60～80年代多干旱,进入90年代雨涝增多,反映华北平原地区旱涝变化阶段性和群发性。东西伯利亚（或鄂霍茨克海）阻塞高压及亚洲中高纬度东高西低分布的稳定维持,则分别对华北平原的严重干旱与雨涝的形成起着重要的作用。西太平洋副热带高压位置偏北、偏西（偏南、偏东）,华北平原地区易发生严重雨涝（干旱）。夏季风偏强（弱）年份,华北平原多发生雨涝（干旱）。 在赤道中东太平洋海温与北太平洋西风漂流区海温处于明显正距平阶段,华北平原地区易分别发生严重干旱与雨涝。  相似文献   

Numerical modeling of vertical drains with advanced constitutive models     

Abdulazim Yildiz 《Computers and Geotechnics》2009

The water flow into a vertical drain under an embankment loading is axisymmetric problem and therefore, the vertical drain system must be converted into equivalent plane strain model. The matching is achieved by manipulating the drain spacing and/or soil permeability according to relatively simple rules. This paper investigates the verification of matching approaches by comparing 2D plane strain and 3D unit cell results when complex constitutive models are used in the finite element analyses. The numerical results showed that the match was found to be satisfactory but not perfect. A full-scale plane strain analysis is subsequently applied to an embankment case history taken from Haarajoki, Finland, stabilized vertical drains and compared with field measurements.  相似文献   

基于GIS技术的运动学岩坡滑动可能性分析     

粟曦违 《四川测绘》2011,(5):202-204

利用运动学原理来分析岩体结构面与岩坡的几何关系,可以识别岩坡滑动破坏的可能性。将运动学与GIS技术相结合构建有代表性的研究区域地质结构面与地形模型,并通过GIS的空间分析功能,提供更加准确、直观、高效的分析结果。最后,运用GIS技术的运动学模型对大岗山水电站坝区岩坡的滑动可能性进行分析,论证了GIS环境下运动学分析的可行性和有效性,以及相对于传统运动学分析的优越性。  相似文献   

VC++编写房产分层分户图检查程序     

张翼翔 《测绘与空间地理信息》2011,34(3):210-212

介绍了VC++6.0编写房产分层分户图检查程序的流程和实现方法,涉及数据库及VC++底层开发的一些知识.  相似文献