长短桩组合多元复合桩基技术的应用研究     

代国忠  李文虎  林道富 《岩土力学》2008,29(Z1):640-644

论述了长短桩组合多元复合桩基的设计原理,分析了复合桩基承载力和地基沉降的计算方法。并结合灰砂桩与CFG桩组合桩基处理工程实例,介绍了按长短桩多元复合桩基设计计算、施工技术和处理效果。实践证明,长短桩复合桩基组合形式多样,不受桩型选择限制,可实现单元组合或多元组合,它能充分发挥桩间土、短桩和长桩三者的潜能,大幅度地减少了长桩的用量,确保地基承载能力,并可有效地控制基础整体沉降和差异沉降,其应用前景广阔。  相似文献   

甘肃中部强沙尘暴成因分析   总被引：1，自引：0，他引：1  

杨先荣  王劲松  何玉春  邓吉录  任余龙  杨文月 《中国沙漠》2008,28(3):567-571

利用1970—2006年甘肃中部13个县（市）的21例沙尘暴天气过程的各时次高空和地面资料,通过分析沙尘暴过程的影响系统,来研究甘肃中部近年来强沙尘暴天气频繁入侵的成因及特点。结果表明:甘肃武威东南部发生沙尘暴天气时,500 hPa高空出现一支风速≥20 m·s-1西北向的急流轴;河西走廊地形的“狭管效应”作用,使沙尘暴移速增快,强度增强,沙尘在翻越乌鞘岭后,相继侵袭白银、兰州、临夏等广大地区;进入21世纪以来,甘肃中部沙尘暴和强沙尘暴次数逐年增多,强度增强、影响范围扩大。  相似文献   

Characteristics of present-day active strain field of Chinese mainland     

郭良迁  李延兴  杨国华  胡新康 《地震学报(英文版)》2008,21(6):562-572

On the basis of the GPS data obtained from repeated measurements carried out in 2004 and 2007,the horizontal principal strain of the Chinese mainland is calculated,which shows that the direction of principal compressive strain axis of each subplate is basically consistent with the P-axis of focal mechanism solution and the principal compressive stress axis acquired by geological method.It indicates that the crustal tectonic stress field is relatively stable in regions in a long time.The principal compressive stress axes of Qinghai-Tibet and Xinjiang subplates in the western part of Chinese mainland direct to NS and NNE-SSW,which are controlled by the force from the col-lision of the Eurasia Plate and India Plate.The principal compressive strain axes of Heilongjiang and North China subplates in the eastern part direct to ENE-WSW,which shows that they are subject to the force from the collision and underthrust of the Eurasia Plate to the North America and Pacific plates.At the same time,they are also af-fected by the lateral force from Qinghai-Tibet and Xinjiang subplates.The principal compressive strain axis of South China plate is WNW-ESE,which reflects that it is affected by the force from the collision of Philippine Sea Plate and Eurasia Plate and it is also subject to the lateral force from Qinghai-Tibet subplate.It is apparent from the comparison between the principal compressive strain axes in the periods of 2004～2007 and 2001～2004 that the acting directions of principal compressive stress of subplates in both periods are basically consistent.However,there is certain difference between their directional concentrations of principal compressive stress axes.The sur-face strain rates of different tectonic units in both periods indicate that the events predominating by compressive variation decrease,while the events predominating by tensile change increase.  相似文献   

高温目标辐射亮度比的方向性研究     

张雪峰  潘军  蒋立军  王凯  仲伟敬  张文哲 《世界地质》2019,(2):522-531

为研究高温目标在短波红外发射辐射的方向性,建立多角度观测物理模型;以燃烧竹炭作为小面元高温目标,在暗室条件下使用ASD FieldSpec3光谱仪对高温目标的辐射亮度进行多角度观测和分析。仅使用一台光谱仪无法同时获取多个角度的观测数据,且以不同角度观测时,高温目标温度发生明显改变,本文采用一种自定义的降温模型计算多角度观测的参比辐射亮度,并提出一个概念-辐射亮度比(多角度辐射亮度/参比辐射亮度),用以消除高温目标降温的影响。结果表明,降温模型精度很高,辐射亮度比这一概念很好地刻画了高温目标在短波红外辐射的方向性,余弦函数、傅里叶级数均可实现对辐射亮度比随角度变化的高精度拟合。  相似文献   

中国大城市用地空间扩展若干规律的探索——以苏州市为例   总被引：13，自引：3，他引：10  

姚士谋  陈爽  吴建楠  张越  陈振光 《地理科学》2009,29(1)

城市用地空间扩展是城市成长发展过程中在物质形态上的具体体现,是城市发育有机成长的各种因素综合作用下的结果.自改革开放以来,由于经济增长迅速,优越区位外资的集聚,开发区的形成,中国大城市的用地空间扩展迅速.经过多年来的建设实践,参照全球经济一体化的背景,结合苏州市个案研究,初步探索了中国大城市用地空间扩展的若干规律,即城市扩展沿交通走廊轴线发展的脉动规律,城市边缘地区定向开发以及城市经济集聚与扩散规律制约下的城市空间扩展过程,按照科学发展观,探索这些规律指导中国的城市规划与建设,构建和谐社会,防止城市用地盲目扩大、用地失控,并促进城市土地开发按资源节约型方向发展,走城市可持续发展,健康城市化的道路.  相似文献   

PLANT COLONIZATION IN CONDESA NIVATION HOLLOW, SIERRA DE GUADARRAMA (SPANISH CENTRAL SYSTEM)     

BY JULIO MUÑOZ JIMÉNEZ  ARTURO GARCÍA ROMERO 《Geografiska Annaler: Series A, Physical Geography》2009,91(3):189-204

The purpose of this study was to determine plant distribution at a nivation hollow located in a Mediterranean high mountain area and to analyse the effects of snow cover, wind exposure, proximity to moisture and the characteristics of the substrate on the vegetation. We analyse these factors and interpret concurrent effects due to recent climate change.
The nivation hollow, called Ventisquero de la Condesa, is located at 2258 m a.s.l., 40°47'10"N and 3°58'35"W, in the Sierra de Guadarrama (Madrid, Spain). We established 579 small sample plots in the study area, and grouped them into 29 transects where snow duration, wind exposure, availability of meltwater, geomorphologic instability and surface rockiness were examined directly and indirectly. The types of plants and the number of individuals per species were registered for each plot to establish ecological affinities among the 28 distinguishable species. Six showed the highest level of chionophily while nine showed the lowest adaptation to snow cover duration. A statistical study incorporating other variables applied in the research revealed that wind exposure, moisture capture and the intensity of geomorphologic dynamics have a highly significant correlation with nivation, while surface rockiness is a virtually independent factor. Due to environmental changes caused by recent global warming, several plant species, especially adapted to survival in snow conditions, coexist in the hollow with saxicolous plants that have invaded the site from adjacent grass and shrublands.  相似文献   

全曲轴坐标系图形量化方法及其在地学信息可视化中的应用   总被引：1，自引：0，他引：1  

仝春艳  张军海  李仁杰  傅学庆 《地理与地理信息科学》2009,25(1)

曲轴坐标系是对传统直线坐标系的扩展,由曲轴坐标系构成的量化图形造型丰富、活泼生动、组合方式多样,是量化图形发展的又一重要途径.全曲轴坐标系是曲轴坐标系统中的一类,是量化图形的数学基础之一.该文通过对全曲轴坐标系的构成、基础坐标网和组合图形的研究.展现了全曲轴坐标系量化图形用于表现各类统计数据的能力.以<2005年中国统计年鉴>为数据源,绘制多种全曲轴坐标系图形图谱并进行分析,对实际的地学统计数据进行直观展现.同时,进行曲轴坐标系量化图形专题制图系统的研发,为全曲轴坐标系在地学信息可视化中的应用提供参考.  相似文献   

倾斜裂隙介质反透射系数研究   总被引：4，自引：3，他引：1       下载免费PDF全文

蔡晓刚  陈晓非 《地球物理学报》2009,52(5):1253-1262

自然界的裂隙排列并非都是直立的,在复杂地壳应力作用下裂隙排列很可能是倾斜的.本文从各向异性弹性动力学基本方程出发,在特征矩阵方法基础上提出了计算任意倾斜裂隙介质水平界面上的反射、透射系数的简单方法,并利用该方法计算了倾斜裂隙介质P-P波、P-SV波和P-SH波的反透射系数.结果表明,P-P波、P-SV波和P-SH波的反透射系数与倾斜裂隙的倾角、测线方位以及偏移距这些物理参数之间存在一定的依赖关系.此外我们计算了C波的零入射相角时的反射系数,发现该反射系数跟裂隙倾角、裂隙的方位角有着明显的对应规律,且各向异性越强时,该反射系数越大.这些研究对于深入了解倾斜裂隙的动力学特征具有一定的意义.  相似文献   

Biweekly periodic variation of the Kuroshio axis northeast of Taiwan as revealed by ocean high-frequency radar     

Daisuke Takahashi  Xinyu Guo  Akihiko Morimoto  Shoichiro Kojima 《Continental Shelf Research》2009,29(15):1896-1907

An analysis of surface current data obtained from 2002 to 2005 using long-range high-frequency radar provides the first evidence for the presence of biweekly (11–14 day) periodic variations of the Kuroshio axis northeast of Taiwan. This analysis clarifies the spatiotemporal characteristics of these variations and reveals that cyclonic/anticyclonic eddies propagating along the shelf slope from the vicinity of the deep channel east of Taiwan induce these variations northeast of Taiwan. The behavior of the cyclonic/anticyclonic eddies on the shelf slope is well explained by 2nd-mode interior shelf waves advected by the Kuroshio's mean flow. Remote effects from the vicinity of the deep channel east of Taiwan, or from outside the East China Sea, are believed to play an important role in the generation of these biweekly periodic variations of the Kuroshio axis northeast of Taiwan. Moreover, on the shelf slope, these variations cause an onshore current across the shelf slope, suggesting topographically controlled upwelling. Therefore, the biweekly periodic variations of the Kuroshio axis northeast of Taiwan might contribute not only to the onshore transport of Kuroshio surface water but also to transport nutrient-rich Kuroshio subsurface water onto the shelf in the East China Sea.  相似文献   

地球基本磁场的成因   总被引：1，自引：1，他引：0       下载免费PDF全文

宋贯一 《地球物理学进展》2009,24(1):89-94

在略高于古藤堡面的压力和温度条件下,地核物质中的原子结构状态发生了质变.如对于外层能级分布是3d64s2的铁原子而言,Fe原子的最外层和极少一部分Fe原子的次外层将受到破坏,使外层电子发生"公有化"现象,残破的原子(处于离子状态)在自引力作用形成的压力作用下,按原子密度的大小产生分异,"内核"多为显示有正电性能的密度较高的残破原子组成,"外核"(包含过渡层)为富含"公有化"电子而显示负电性能的密度相对较低的残破原子组成,这是一个地核物质量子状态变化的静态过程,从地球内部宏观电性结构看来,地球的"内核"和"外核"组成缮了一个静态的巨型似"原子球","外核"显示负电性,"内核"显示正电性,"内核"所带电量与"外核"所带电量相等,但符号相反,在静态的情况下,似"原子球"并不显示磁性.由于地球自转,"外核"上界面赤道上的自转线速度为252.9m/s,"内核"外界面赤道上的自转线速度为88.9 m/s,二者的速度差为164.0 m/s,这种含有由巨大电量的"外核"电子壳层相对"内核"绕固定的轴向(自转轴)转动,自然会形成它的基本磁场.  相似文献