共查询到20条相似文献，搜索用时 31 毫秒
1.
There are numerous methods to prevent seepage flow and ground improvement methodologies such as cement grouting, sheet piling, and the membrane method. In this paper, we present case histories of freezing technology applications in the construction of a deep tunnel sewerage system, undersea highway tunnel, and liquefied natural gas tank. Heaving pressure measurements for various soil types around a liquefied natural tank are compared with existing data. In this paper, we present temperature variations at the bottom and side of a liquefied natural gas tank. Our findings show that ground-freezing technology is very effective in controlling ground water infiltration into underground structures as well providing soil reinforcement in the soft ground. 相似文献
2.
Kazakhstan regions is seasonal climatic with transient freezing of soil groundduring the winter. Roadbed integrity is important to resist the sustained load transmitted by traffic on the road surface. Freezing of soil ground could significantlyinfluence roadbed integrity in the seasonal freezing climate of Kazakhstan. The proper determination magnitude of frost heave and heaving pressure by the influence of freezing temperatures during the winter season are necessary for design and construction of highways. Thus, experimental tests were conducted on specimens obtained from Astana (Kazakhstan) to determine the freezing pressure and magnitude of frost heaving. 相似文献
3.
跨江通道是支持城市跨江发展的重要设施,能有效地突破天然水系阻隔并加速各类生产要素的跨江流动,可有力地促进滨江副城的城市发展与土地增值。本文提出地价趋势分离法,借助GIS空间分析工具,以南京市浦口区为例开展跨江通道对滨江副城住宅地价增值的测算研究。结果表明:单通道各区段的住宅地价梯度及通道贡献值随着与通道节点距离的增加呈现出逐级递减现象,多通道作用下住宅地价的增值效应则呈多中心的波浪推移模式;2020年,各跨江通道节点区域通勤类通道对住宅地价的增值约为一级基准地价的52.54%,过境类通道仅为31.52%,同时可测算到多通道作用下"浦口新城"住宅地价的溢价潜力高达404.76亿元,这将为浦口区城市基础设施建设筹集大量资金,利于切实贯彻南京市的城市跨江发展战略。 相似文献
4.
敦煌莫高窟古代生土建筑物风蚀机理与防护对策的研究* 总被引：1，自引：1，他引：1
利用低温冻融实验和风洞模拟实验研究古代生土建筑的风蚀机理,结果表明:挟沙风风蚀速率明显大于净风的风蚀速率,其风蚀率是净风的130倍,冻融是风蚀速率增大的一个重要因素,偏西风的降水和风蚀是造成莫高窟古代生土建筑风蚀毁坏的方要原因.实验表明,采取5%LS和10%PS防护材料是防止风蚀的一条重要途径. 相似文献
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长江下游地区过江通道发展利用与“时空压缩”的演变特征 总被引：1，自引：1，他引：0
长期以来过江通道供需矛盾突出,高效利用现有通道并合理规划建设新通道设施、吸引两岸要素无障碍流动成为长江下游地区率先实现跨江发展、推进次区域合作的基本物质保障。基于此分析2000年以来长江下游地区公路过江通道建设对南北岸间交通的“时空压缩”效应,尝试探讨高等级公路网体系中过江通道通行利用空间特征。研究时段内过江通道建设实现由点到面扩张,从单一到多样化的跨江条件改善压缩区位差异对发展造成的不公平,跨江时间成本逐渐转变为自岸向两侧的由高到低梯度推移。沿岸地区就近选择过江通道,中远岸市县由高等级公路网引至特定通道方向,完整的过江通道是包含跨江桥隧和后方高等级连接公路的交通走廊。各通道因其在路网体系中的定位不同,通行利用存在差异,区域空间和基础设施建设的有限性要求建立“干线公路-跨江桥隧”多对多选择,提升既有通道通行能力并将连接道路建设向新通道方向倾斜,以分流通行压力并缩小区域内跨江成本差距。 相似文献
7.
In-situ tests and numerical manipulations were conducted for comparison of superior/inferior quality of casing-tube-vacuumized
insulation and polyurethane insulation of freezing apparatuses in relation to non-uniform cold distribution in the multi-coil freezing
layout and the contradiction between large-coil diameter layout of the freezing holes and stability of the headframe base. Tests
show that: (1) under current technology, vacuumized insulation is of short duration due to lack of appropriate applied vacuum; (2)
after the freezing pipe is insulated with polyurethane, the temperature gradient is less than no insulation, and the temperature difference
between insulated and non-insulated apparatuses is stable as the freezing period increases. Finally, it is pointed out that
polyurethane insulation is quite efficient in present technical freezing construction. 相似文献
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Seasonally cold climate and resulting frost action set great demands to railway track substructure in order to maintain track geometry. Challenges
culminate on high-speed lines, where the tolerances for roughness are the tightest. Problems may result in highly increased track
maintenance and need for temporary speed restrictions. The causes of frost action can be associated with subsoil, subballast or ballast. The
major concern in frost protection is to avoid the freezing of frost susceptible subsoil by using sufficient thickness of subballast and relying on
non-frost-susceptible subballast material. This paper provides an overview of the main research findings on the role of ballast, subballast and
subsoil in frost action. In new construction the material specifications, design procedures and construction methods have been developed to
ensure adequate performance of track substructures, but special challenges exist in managing existing tracks that were not designed for
modern requirements. In order to perform cost-effective and sustainable track maintenance, it is necessary to recognize the problem areas and
define the root-causes of problems. For locating the problem sections and defining the causes of defects, a sophisticated analysis based on
integration of track geometry and ground penetrating radar (GPR) data has been developed and is summarized in this paper. 相似文献
10.
运营隧道渗漏水灾害分类和等级评定方法 总被引：1，自引：0，他引：1
通过对国内95条具有代表性的南、北方运营隧道渗漏水状况调查,和对影响隧道渗漏水病害的各类因素综合分析,选择了隧道的埋深、地下水水位与隧道底板的高差、隧道区的降雨量、隧道区的植被情况、三缝的施工、管道腐蚀与堵塞情况等16个子因素(其中4个定量因素、12个定性因素),从隧道施工因素,防排水工程措施、围岩及地下水因素、自然地理因素等四个方面建立了隧道渗漏水灾害的评价指标体系和层次分析模型.并按照衬砌漏水量大小及渗漏状态;渗漏部位以及渗漏形式;隧道灾害的严重程度分别对隧道渗漏水灾害进行分类,确定了16个子因素的五等级划分标准,并分别量化了定量和定性指标,建立了隶属函数,最后利用模糊综合评价方法对隧道渗漏水灾害等级进行评定,同时用VB编制了评价的可视化程序,为设计和施工单位预防隧道渗漏水灾害提供了理论依据. 相似文献
11.
Sergei Kudriavtcev Tatiana Valtsev Alexei Kazharskyi Elena Goncharov Iurii Berestianyi 《寒旱区科学》2013,5(4):0404-0407
The goal of a predictive thermotechnical calculation is to model the behavior of the top permafrost boundary under current
operational conditions as well as increasing average annual air temperatures that results in degradation of the permafrost
layer. Numerical modeling was used to assess the efficient application of construction measures to create sustainable operation
of the railroad. The numerical modeling was carried out in the programming complex FEM-models developed by
geotechnical engineers of St. Petersburg, Russia under Prof. V. M. Ulitsky’s guidance. The Termoground Program as a part
of the FEM-models enables the research of freezing, heaving and thawing in different design solutions. Research was
carried out in space resolution for a year cycle. The performed model has shown that the designing measures accepted for
permafrost protection from retreat in the subgrade support were generally effective. 相似文献
12.
Frost heave is one of the main freezing problems for construction in permafrost regions.The Konrad-Morgenstern segregation potential（SP） model is being used in practice for frost heave using numerical techniques.However,the heat release from in-situ and migrated water in the freezing zone could result in some numerical instability,so the simulation of frost fringe is not ideal.In this study,a semi-analytical solution is developed for frost heave prediction of clay soil.The prediction results to the two tests with different freezing mode with clay soil agree well with the tested behavior,which indicates the feasibility of the solution. 相似文献
13.
可移动式环境风洞气动特性测试与评价 总被引：1，自引：0，他引：1
对中国科学院新疆生态与地理研究所新建的可移动式环境风洞进行了流场测试,分析评价该风洞气动特性,期望对今后的风洞实验开展有所指导。本实验在室内进行,在空洞条件下,用皮托管测量不同风速下（7 m·s-1,12 m·s-1,16 m·s-1）实验段截面风速分布沿流向的变化,测试内容包括风洞实验段的气流稳定性、横向均匀性、紊流度、边界层厚度的分布规律,并与其他环境风洞相比较。结果显示,该风洞气流稳定性系数小于1%,横向不均匀度小于2.5%,紊流度在1%左右,底板边界层和侧壁边界层分别为15 cm和10 cm,表明该风洞使用效果良好,设计合理。 相似文献
14.
跨江发展下杭州市企业迁移空间模式及影响机制 总被引：2，自引：2，他引：0
基于企业微观主体视角,运用UCINET社会网络分析和ROST内容分析法,对杭州市企业迁移的空间模式和区位选择进行探讨,并揭示其影响机制。研究表明：① 杭州市企业迁移分为平缓波动期、低速增长期、大规模迁移期、迁移成熟期4个阶段,与杭州市跨江发展历程基本相契合。② 杭州市企业总体迁出呈中心-外围衰减分散布局模式,迁出地点主要集中于西湖区、下城区及拱墅区,迁出企业主要为制造业,批发零售业等;总体迁入呈中心、外围集聚模式,迁入地主集中于西湖区、余杭区及滨江区,迁入企业主要为信息技术服务业、科学研究和技术服务业。③ 企业的自身属性与外部环境对杭州市企业迁移有着重要影响,企业异质性在很大程度上决定着企业迁移的方向;跨江发展战略中的政府推动、市场运作、企业参与、文化根植等外部因素对企业迁移的空间选择有着极其重要的作用。 相似文献
15.
花岗岩残积土开挖边坡的工程特性 总被引：6，自引：0，他引：6
为研究开挖效应对花岗岩残积土工程特性的影响,进行压缩性和抗剪强度试验,研究应力卸荷、饱和软化、失水干缩的影响以及注浆加固效果,然后从几何微结构及其损伤角度,研究其开挖边坡滑动的微观机理,主要结果有:边坡开挖后,随着临空面的形成和暴露,失水干缩、应力卸荷及饱和软化等开挖效应将导致土体弱化,而且当它们共同作用时,弱化效应叠加;对花岗岩残积土注水泥浆,可修复并增强土体的微结构,减弱开挖效应;提出的微结构几何模型,基本反映了花岗岩残积土的微观特征,可较好地解释开挖效应,揭示开挖边坡的滑动破坏机理。研究成果可为花岗岩残积土开挖边坡防护的设计、施工及新技术研究提供概念上指导和参考。 相似文献
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After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons,while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change. 相似文献
18.
青藏铁路沿线1966-2004年冻结与融化指数的变化趋势 总被引：1，自引：0，他引：1
利用日气温观测值计算了青藏铁路沿线7 个主要气象站1966-2004 年的年冻结与融化指数,分析了这些指数的统计与分布特征,并应用两种趋势检验方法：非参数Mann-Kendall 检验法和简单线性回归法分析了这些台站年冻结与融化指数的变化趋势。结果表明,青藏铁路沿线多年平均冻结指数大致分布在95~2300 oC·日之间, 多年平均融化指数大致在630~3250 oC·日之间。7 个站点的冻结指数均呈减少趋势,其线性倾向率分布在-16.6~-59.1 oC·日/10a 之间;融化指数均呈增加趋势,其线性倾向率分布在19.8~45.6 oC·日/10a 之间。MK 趋势检验的结果显示,除格尔木表现出微弱的减少趋势外,其他站点都呈现了0.05 水平 下的显著减少趋势;年融化指数除格尔木和沱沱河表现出弱增加趋势外,其他5 个台站都显示出了0.05 水平下的显著增加趋势。简单线性回归方法得到的趋势结果与MK 趋势检验结果相一致。 相似文献
19.
不同下垫面对风沙流特性影响的风洞模拟研究 总被引：20，自引：5，他引：15
通过对戈壁、草方格和流沙地表风沙流特性的风洞模拟实验,探讨不同性质下垫面对风沙流结构和风沙活动层风速廓线的影响,从而为野外工程防沙的优化设计及其应用提供理论依据。实验结果表明：戈壁地表风沙活动层主要集中在距地表20cm高度范围内;由于沙颗粒与戈壁地表的砾石发生碰撞．输沙率随高度的分布不再简单的遵循对数关系,其极值出现的高度随风速的增加而上移。由于草方格构成的下垫面复杂多变,其对风沙流结构与风沙活动层风速廓线的影响很难确定。但对于特定的下垫面,在不同风速下．同一高度层含沙量具有很大的相关性。 相似文献
20.
The paper presents some methods of numerical modeling and a study of moisture changing in frozen clay soils considering rates of freezing in the base of construction.An impact assessment of moisture changes in clay soils affecting strength characteristics during thawing was carried out in stability tests. 相似文献