DTM在公路设计中的应用     

黄桂兰 《武汉大学学报(信息科学版)》1989,(3)

经济建设的发展必然对公路建设的发展规划、测设手段、装备等提出变革的要求。加快公路设计速度主要靠自动化,而地形资料的数字化(即数字地面模型DTM)是公路设计自动化的不可缺少的工具。本文建立了在取样及数据处理上始终考虑到公路设计及线型工程特点的DTM;编制了人-机配合设计纵断面程序,计算各种地质类型的土、石方程序,利用计算机联绘图机绘制任意长度的纵断面图、平面图、指定桩号的横断面图、透视图绘制程序,并用实际资料验证了程序的正确性。研究与试验表明:DTM用于公路设计不仅可行,且大有潜力可挖。  相似文献   

Appraisal of ground vibration from civil engineering construction     

P. B. Attewell  A. R. Selby  A. Uromeihy 《Geotechnical and Geological Engineering》1989,7(3):183-208

Amplitude and style of ground vibration from two types of pile driving — vibrodriver (periodic) and drophammer (transient) — are considered for the analysis of deformation in a portal frame structure. It is argued that the three-dimensional character of the vibration should be determined in the form of a resultant vector and this requires the measurement of vibration in three directions at right angles together with information on the sense of the motion along each orthogonal axis of vibration. Such resultant vector data during the period of vibration are best processed and presented in the style of a suite of hemispherical projections that comprise upper and lower hemisphere forms, respectively embodying components of upward and downward vibrational motion. It is shown that analysis for the dynamic stability of a simple block foundation is assisted by reference to the hemispherical projection representation and by the use of ground surface acceleration data.  相似文献   

A convenient device for hemispherical projection plotting in rock mechanics     

Ali Uromeihy 《Geotechnical and Geological Engineering》1988,6(2):163-168

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北极地区不同冰龄的海冰厚度变化研究   总被引：1，自引：0，他引：1  

毕海波  付敏  孙科  刘一霖  徐秀丽  黄海军 《海洋学报(英文版)》2016,35(10):1-10

In this study, changes in Arctic sea ice thickness for each ice age category were examined based on satellite observations and modelled results. Interannual changes obtained from Ice, Cloud, and Land Elevation Satellite(ICESat)-based results show a thickness reduction over perennial sea ice(ice that survives at least one melt season with an age of no less than 2 year) up to approximately 0.5–1.0 m and 0.6–0.8 m(depending on ice age) during the investigated winter and autumn ICESat periods, respectively. Pan-Arctic Ice Ocean Modeling and Assimilation System(PIOMAS)-based results provide a view of a continued thickness reduction over the past four decades. Compared to 1980 s, there is a clear thickness drop of roughly 0.50 m in 2010 s for perennial ice. This overall decrease in sea ice thickness can be in part attributed to the amplified warming climate in north latitudes. Besides, we figure out that strongly anomalous southerly summer surface winds may play an important role in prompting the thickness decline in perennial ice zone through transporting heat deposited in open water(primarily via albedo feedback) in Eurasian sector deep into a broader sea ice regime in central Arctic Ocean. This heat source is responsible for enhanced ice bottom melting, leading to further reduction in ice thickness.  相似文献   

我国西北降水变化趋势和预估     

张诗妍  胡永云  李智博 《气候变化研究进展》2022,18(6):683-694

利用观测资料、GPCC再分析资料和第六次耦合模式比较计划（CMIP6）模拟结果,研究了我国西北地区近几十年及未来降水变化趋势。结果表明,1979—2019年我国西北干旱半干旱区降水在全年各季节均有显著增加,其中秋季增加最多。CMIP6模拟结果显示,随着全球变暖,我国西北地区降水在2015—2100年将继续增加。至21世纪末,在SSP2-4.5和SSP5-8.5情景下,我国西北地区年平均降水量将分别增加约13.7%（37 mm）和25.8%（78 mm),其中降水量增加最多的季节分别为夏季和春季。考虑到西北地区蒸发量也将随全球变暖而增加,模式平均的结果显示西北地区年平均净降水量在两种情景下的增幅分别约1.4%和4.9%,表明我国西北地区未来气候呈现显著的变湿趋势。进一步分析表明,西北地区未来降水增加可能与局地大气低层位势高度降低和上升运动加强有关。  相似文献   

CMIP6模式对亚洲中高纬区极端温度变化的模拟及预估          下载免费PDF全文

蒋文好  陈活泼 《大气科学学报》2021,44(4):592-603

利用观测的亚洲中高纬区逐日最高、最低气温和CMIP6计划中28个全球气候模式资料,系统评估了CMIP6模式对亚洲中高纬区日最高温(TXx)和日最低温(TNn)的模拟性能,并对其未来演变趋势进行了科学预估。主要结论如下:1)CMIP6大部分模式能合理地模拟亚洲中高纬区TXx和TNn自南向北、自西到东逐渐降低的空间分布特征,但所有模式均在青藏高原北部地区附近存在较大的冷偏差。模式对气候平均态的模拟一致性较好,对TNn的模拟优于TXx;但是对于趋势变化模拟,对TXx的模拟与观测更为接近,而且多模式集合的模拟效果更优。2)预估结果指出,日最高气温和最低气温在21世纪均表现出显著增温趋势,其中TNn增加趋势更加明显。在SSP5-8.5排放情景下,到了21世纪末期,TXx约增加7.0℃,TNn约增加9.6℃。此外,预估结果不确定性随时间推移、排放增多而增加,其中对于TXx的预估结果可信度更高。  相似文献   

全球气候变暖:浅谈从AR5到AR6的认知进展   总被引：2，自引：0，他引：2       下载免费PDF全文

周波涛 《大气科学学报》2021,44(5):667-671

自政府间气候变化专门委员会（IPCC）第五次评估报告（AR5）发布以来,国际科学界在气候系统变化领域取得显著进展,有关气候变化的科学认识不断深入。IPCC第六次评估报告（AR6）第一工作组（WGI）报告对这些科学进展和最新认识作了综合评估。温度是全球变化最直接的指示器。本文从温度变化视角,对从AR5到AR6的科学进展进行了梳理和简要评述,主要聚焦观测的变化、归因以及未来预估三个方面。与AR5相比,AR6以更强有力的证据进一步确证了近百年全球气候变暖的客观事实,人类活动对气候变暖影响的信号更为清晰,未来变暖幅度取决于温室气体减排力度。  相似文献   

丹海高速公路平面坐标系的选择     

裴书琦  陈乃桥 《吉林地质》2006,25(2):74-79

对地处山岭、重丘、平原区域的公路勘测线路,进行了具体分析,提出若建立多个抵偿高程投影面坐标系,虽不完全适合GPS控制网的整体平差计算,但可建立公路地固平面坐标系,以解决投影长度变形问题,从而满足公路勘测的实际需要。  相似文献   

湖南黄沙坪铅锌矿深边部找矿前景分析   总被引：9，自引：0，他引：9  

许以明  龚述清  江元成  雷泽恒  李玉生 《地质与勘探》2007,43(1):38-43

湖南黄沙坪铅锌矿是我国重要的铅锌原料生产企业,是湖南省内最大的铅锌开采矿山和铅锌原料生产基地.由于矿山长期开采,近几年矿山已处于资源危机状态,为保障黄沙坪矿持续稳定发展,势必要研究、寻找、控制矿区深部(垂深500 m以下)、边部隐伏的铅锌矿.文章在分析前人资料的同时,通过分析研究区内铅锌矿控矿地质条件、成矿规律及成矿预测靶区等,对黄沙坪铅锌矿深边部铅锌矿的资源前景进行了初步分析,为开展矿山深边部找矿工作提供依据.  相似文献   

Parallels plane projection and its geometric features     

ZHOU ChengHu  MA Ting  YANG Liao  QIN Biao 《中国科学D辑(英文版)》2007,50(Z1):176-180

A new equivalent map projection called the parallels plane projection is proposed in this paper. The transverse axis of the parallels plane projection is the expansion of the equator and its vertical axis equals half the length of the central meridian. On the parallels plane projection, meridians are projected as sine curves and parallels are a series of straight, parallel lines. No distortion of length occurs along the central meridian or on any parallels of this projection. Angular distortion and the proportion of length along meridians (except the central meridian) introduced by the projection transformation increase with increasing longitude and latitude. A potential application of the parallels plane projection is that it can provide an efficient projection transformation for global discrete grid systems.  相似文献