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在我国社会经济飞速发展的背景下,基础建设项目越来越多,土方量计算是工程项目建设的关键环节,土方量计算的精度,对建设成本、建设质量等方面有较大影响,因此,在动工建设之前,需要选择科学的计算方法,来保证土方量计算的精度。传统水准仪量计法、全站仪量计法等存在一定的局限性,无法从全局的角度来开展土方量计算。低空摄影测量技术的发明和应用有效弥补了这一段短板,以其高机动性、高灵活性、高分辨率、高效率的优势,自发明以来就深受土方量计部门的青睐。基于此,本文结合理论实践,先分析了低空摄影测量技术的基本概念,接着论述了此项技术在土方量计算中应用的可行性,并结合具体的工程实例,分析了土方量计算中融入低空摄影测量技术的过程,希望对提升土方量计算精度有一定参考和帮助。 相似文献
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土方量计算是高速公路建设中最重要的环节之一,其计算的准确性直接关系到项目各参与方的经济利益,所以精确计算土方量对于高速公路建设至关重要。本文针对此问题,提出基于倾斜摄影技术计算土方量的方法,该方法不仅弥补了传统测量方式作业难度大且效率低的问题,而且土方量计算精度也能满足规范要求;该方法验证了基于倾斜摄影技术计算土方量的可行性和适应性,并具有较高的鲁棒性,为以后快速高效、精确计算土方量提供了一种有效途径。 相似文献
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谈了长输管道工程管沟土方量的计算方法以及Excel在管沟土方量计算中的应用并分析了管沟土方量的计算公式。 相似文献
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不规则三角网法是土方量计算的常用方法,其计算精度受高程中误差、地形、三角网平均边长等因素的影响。为研究影响土方计算精度的因素,依据误差传播定律,建立不规则三角网法土方计算精度数学模型。实验部分使用地面三维激光扫描仪获取实地点云数据构建数字地面模型(digital terrain models, DTM)模拟真实地形得到区域土方量真值,然后利用不规则三角网法计算区域土方,对高程中误差、边长进行精度影响分析。实验表明三角网边长对土方量计算精度影响显著,需要严格把控;而高程中误差对土方量计算精度影响不明显,将点位的高程精度控制在厘米级即可。 相似文献
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Glynn AW Wernroth L Atuma S Linder CE Aune M Nilsson I Darnerud PO 《The Science of the total environment》2000,246(2-3):195-206
Results from the Swedish control programme regarding organochlorines in food were used to determine time trends of organochlorine concentrations in adipose tissues from swine (4-8 months old) and bovines (non-dairy, 12-36 months) slaughtered between 1991 and 1997. Moreover, possible regional differences in concentrations were studied, as well as differences in concentrations depending on sex and age of the slaughtered animals. Multiple linear regression indicated that the concentrations of PCB, p,p'-DDE, HCB and alpha-HCH decreased by 4-17% per year, suggesting that the decline in organochlorine concentrations in the Swedish environment and biota reported during the 1970s-1990s also has occurred in meat-producing animals during the 1990s. The concentrations of PCB, DDE and HCB in bovines and PCB and DDE in swine were 1.4-3.8-fold higher in the southern parts of Sweden than in the northern parts of the country, indicating a regional difference in exposure of the animals. The organochlorine concentrations were higher in bovines than in swine, and declined faster in swine than in bovines. Moreover, the concentrations of CB 153 and p,p'-DDE were similar in bovines, but in swine the average concentrations of the two compounds differed two-fold. Apart from possible species differences in metabolism of organochlorines, this may be due to differences in the age at slaughter between swine and bovines, and differences in husbandry of the animals. In the latter case, swine are generally kept inside during their whole life span, whereas bovines are kept outside grazing during the summer period. Finally, a sex-dependent difference in concentrations was indicated in swine, but not in bovines. Our study shows that a lot of information can be 'extracted' from control program results. 相似文献
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在1950至1970年代的城市化快速发展时期,法国在城市边缘和郊区进行了以大型住区为主要形式的大规模社会住房建设,虽然有效缓解了战争破坏和人口增长带来的住房短缺,却因廉租性社会住房在城市特定地区的大量集聚,以及大型住区本身存在的选址远离中心、建筑形式单调、空间尺度夸张、建设质量低下、设施配套缺失等不足,在1960年代末和1970年代初引发了居住空间的社会分化现象,并在1980年代随城市社会经济结构转型而不断加剧,迫使法国城市不得不从社会、经济、环境、设施和住宅建设等多方面入手,通过实施一系列城市政策和项目计划,对其进行综合整治和更新改造,以抵制社会排斥,鼓励社会混合,促进城市整体和谐发展。文章通过梳理法国社会住房的发展历程,特别是城市快速发展时期社会住房的建设发展,总结其中的经验教训,旨在为当前处于快速发展时期的中国城市的社会住房建设提供有益的启发和借鉴。 相似文献
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日本地震简介和日建设计的抗震设计 总被引:3,自引:0,他引:3
为更好地帮助读者理解本刊各篇论文的内容,本文简要介绍日本的地震状况,日建设计对地震设计的考虑方法,以及日建设计的设计用人工模拟地震波。 相似文献
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混凝土在现代工程建设中占有重要的地位。而在现代混凝土工程中裂缝几乎无所不在。尽管我们在施工中采取各种措施,但裂缝时有出现,究其原因,发现产生裂缝的原因是多方面的。首先,在施工中混凝土常常出现温度裂缝,影响到结构整体性和耐久性;其次,施工工艺不熟,浇注方式的变化也会导致现浇钢筋混凝土楼板产生裂缝;第三,在运转过程中,温度变化对结构的应力状态具有显著的不容忽视的影响,另外施工单位为赶进度,在现浇混凝土未达到设计强度时即拆模,或板上施工堆载过重,也会导致板开裂,出现穿透性裂缝。本文以近年来部分住宅楼用户投诉件为例,针对混凝土裂缝的成因,从脆性和不均匀性、施工工艺、温度应力形成过程、混凝土的早期养护等方面进行分析,提出现场混凝土温度的控制和预防裂缝的措施。 相似文献
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探究“虚实”空间关系,创造个性化的城市空间场所 总被引:1,自引:1,他引:1
作者利用空间的“虚、实”概念,结合格斯塔心理学的“图底”关系,类比分析中国水墨画的留白艺术手法及生态系统中的细胞繁衍规律,通过张家界城市绿化广场周边地段的概念设计的创作实践,提出创造个性化的城市空间场所工作中虚实空间的理念与原则目标。 相似文献
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Martin Mihaljevi? Vojtěch Ettler Petr Drahota Ladislav Strnad Josef Zeman 《The Science of the total environment》2010,408(6):1286-1294
The weathering of arsenopyrite (FeAsS) has been monitored in soils using an in situ experimental approach. Arsenopyrite in nylon experimental bags was placed in individual horizons in soils in spruce (litter, horizons A, B, and C), beech (litter, horizons A, B, and C) and unforested (horizons A, B, and C) areas and left in contact with the soil for a period of 1 year. The individual areas on the ridge of the Krušné hory Mts., Czech Republic, had the same lithology, climatic and environmental conditions. Scorodite (FeAsO4·2H2O) was identified as a principal secondary mineral of arsenic (As) formed directly on the surface of the arsenopyrite. Scorodite was formed in all the areas in all soil horizons. The amount of scorodite formed decreased in the series beech, spruce and unforested areas. In forested areas, there was a larger amount of scorodite on arsenopyrites exposed in organic horizons (litter, A horizon). The greater rate of arsenopyrite alteration in organic horizons in the beech stand compared to spruce stand is probably a result of faster mineralization of organic material with resulting production of nitrate and better seepage conditions of soil in this area. Speciation of As determined using the sequential extraction technique demonstrated that As was bonded in the soils primarily in the residual fractions prior to the experiment. The As content in the mobile fractions increased in the organic horizon in the forested areas after the experiments. 相似文献
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清末广州中西交汇,景园营造新旧共存互动,推
动岭南园林的近代转型。其中,在繁荣的中西贸易和文化交
流,以及书院文化、士绅文化等的影响下,清末岭南形成了
以广州为中心、十三行行商为代表、官商士绅竞相造园的特
殊历史时期,其造园数量、规模、意匠等均在该时期达到岭
南古典园林发展的巅峰。这一时期也是岭南园林近代转型的
关键时期。在西方文化和清末洋务运动思想的影响下,广州
开始出现洋务花园、公园、市政绿化,以及校园绿地等新型
园林形式。这些具有公共性质的城市景致与新建私园一道广
泛分布在城墙以外,成为清末广州城市空间拓展与风景体系
形成的重要参与者。由于清末广州城外造景的繁荣,从时间
上开启了岭南园林的近代转型,在空间上使岭南园林的地域
性特征得以形成和辨识,其空间性与时间性界定了清末岭南
园林近代转型的物质及文化维度。梳理了清末广州具有代表
性的景园营造活动,在分析其动力机制的同时,探讨城外造
景之于岭南园林近代转型的意义。 相似文献
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Trace elements Cd, Zn, Cu, As, Se and Hg were analysed in muscle and liver of Brünnich's guillemot, Common guillemot, Puffin, Black guillemot, Little auk, Razorbill, Common eider, King eider, Glaucous gull, Herring gull, Black-legged kittiwake, Northern fulmar and Arctic tern collected in 1991-1992 at the main breeding colonies in the Barents Sea. The highest levels of the most toxic elements Cd and Hg were found in birds nesting north of Spitsbergen. Extremely high levels of As were detected in tissues of all seabird species collected at colonies in Chernaya Guba (Novaya Zemlya), where nuclear tests were carried out in the 1960s. In general, levels of all of the trace elements in the Barents Sea seabirds were similar or lower in comparison with those reported for the same seabird species from the other Arctic areas. Data on metallothionein concentrations in different seabird species need to be collected in order to understand the mechanism of bioaccumulation and possible toxic effects of trace elements in Arctic seabirds. 相似文献