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1.
青藏铁路冻土区路桥过渡段沉降原因分析 总被引：4，自引：4，他引：0
青藏铁路开通近10 a以来,各类冻土工程稳定,保证了列车平稳安全的运行。然而,青藏铁路工程也不可避免出现了一些病害问题。现场调查资料表明,冻土区路桥过渡段下沉现象较为严重。通过冻土区路桥过渡段的沉降特点和工程地质条件综合分析,结果表明：地表水或冻结层上水水热侵蚀,引起人为多年冻土上限下降、高含冰量冻土层融化,致使路基发生强烈的融化下沉。建议这类工程病害应采取主动降温措施增强地基土的冻结能力,并加强防排水设施和改善地表水条件,消除水热侵蚀所产生的融化下沉。研究结果为青藏铁路路桥过渡段的稳定性和养护提供了科学依据。 相似文献
2.
寒冻地区铁路隧道气温状态 总被引：7，自引：0，他引：7
本文根据实测资料论述了寒冻地区铁路隧道内的气温状态,给该地区隧道防冻及排水设计提供了依据,并指出在寒冻地区非多年冻土中开挖隧道后有可能形成多年冻土。 相似文献
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In cities, the existence of impervious structures, such as road pavements, parking lots, footpaths, sidewalks, and roofs, can limit the magnitude of rainfall infiltration greatly. Stormwater run-off in storm sewer often dominates, which can cause problems of urban flooding easily during heave rainfalls. In rain and sewage diversion, perforated storm sewer is proposed to enable the occurrence of stormwater infiltration into the ground, which can change the prolonged drought-like condition. Model-scale laboratory tests are conducted to assess the infiltration process of water through drainage holes around the sewer circumference. The experimental data are also used to calibrate a numerical model, after which numerical parametric analysis is carried out. It is found that the feature of drainage holes only influences the wetting front in the initial stage of infiltration. In the end, the egg-shaped contour of wetting front with greater influencing zone below the sewer is obtained. The cumulative infiltration with time can be described by an infiltration model, which is positively correlated with the diameter and the number of drainage holes. The optimal opening ratio is recommended as 0.25%, which can provide the most effective drainage capacity.
相似文献5.
天山玛纳斯河冬季径流对暖冬和冻土退化的响应 总被引：11，自引：5，他引：6
天山高山地区大范围为冻土区,冻土的存在对水文过程有极大的影响.20世纪90年代以来,玛纳斯河流域气温10 a升高了0.54℃,以冬季升温为主,降水量没有增加趋势.应用1957—2004年近48 a的气候和水文月资料,研究了具有多年冻土的高海拔河流的冻土和水文响应.检测到12月至翌年2月气温升高0.8~0.9℃时冬季径流量响应显著,冬季径流在12至翌年2月份增加了14%~26%,其中1月份增加26%.遥相关分析表明,10~11月的水量增大也可导致冬季河流水量增多,1.5~3.0 m的活动层的深度和温度变化导致了这些响应.冻土区的冬季径流水文响应比气温更快、更显著.但冻土和积雪观测的不足使冬季水文变化具有不确定性. 相似文献
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Wanfang Zhou 《Environmental Geology》2007,51(6):963-973
Flooding in karst terranes is a commonly occurring geo-hazard. It causes damage to property, businesses, and roadways. It
can lead to the formation of cover-collapse sinkholes and groundwater contamination. Generally, three types of flooding or
their combinations are related to karst: recharge-related sinkhole flooding, flow-related flooding, and discharge-related
flooding. Understanding of the type of flooding is essential for solving the flooding problem. Areas prone to karst flooding
should be recognized, and restrictions and laws on land use should be implemented. Runoff and erosion control plans should
address the unique characteristics of karst features. Digging out clogged sinkholes, creating retention basins, or installing
Class V Injection Wells are possible solutions to improve drainage of storm water. Solutions to flooding problems in karst
areas should also be coordinated with the water quality control to prevent groundwater contamination. 相似文献
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路基施工对青藏高原多年冻土的影响 总被引：2，自引：2，他引：0
青藏高原上施工会扰动其下多年冻土的存在状态. 近些年来, 高原上相继修建的大量的线性工程, 这些大型工程的建设必将进行多年冻土区的开挖和夯填, 从而会引起下伏多年冻土的结构发生很大变化. 研究了路基施工对青藏高原多年冻土的影响, 并以青藏铁路、青藏公路沿线典型实例进行分析. 结果表明: 开挖施工扰动最大, 可引起斜坡失稳滑塌、地表积水和热融湖塘等;填土路堤会引起其下伏多年冻土升温, 路基两侧形成的小气候往往起着提高地面温度的作用;挡水、排水设施施工也会导致多年冻土上限下降, 地表沉陷. 可见, 填土路基、开挖、地表工程扰动都会导致多年冻土发生变化, 这些冻土变化对路基稳定必将构成威胁. 相似文献
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Evaporite Dissolution Subsidence in the Historical City of Calatayud,Spain: Damage Appraisal and Prevention 总被引：6，自引：0，他引：6
Calatayud in NE Spain is an historically important city built on recent alluvial deposits underlain by gypsum and other soluble rocks. Since its foundation by the Muslims in 716 A.D., the city development has been strongly influenced by geohazards including flooding, subsidence and slope movements. Most of the flooding problems have been mitigated by diversion of the local drainage. However, dissolution of the evaporite bedrock in the urban areas continually causes subsidence and triggers rock-falls from the gypsum cliffs overlooking the city. Subsidence is also caused by the hydrocollapse of gypsiferous silt in the alluvial fan deposits. Building damage in the city was surveyed using a classification scheme developed originally to record damage in British coal mining areas. The Calatayud damage survey shows that the worst building subsidence is concentrated along the line of a buried channel that runs underneath the gypsiferous silt alluvial fan. Natural subsurface drainage causes the dissolution and subsidence, which is aggravated by leakage from water and sewage pipes. Some building damage has been exacerbated during reconstruction by incomplete piling leaving buildings partially unsupported. Mitigation measures include the control of water leakage by the installation of flexible service pipes. Careful construction techniques are needed for both conservation and new developments, especially when piled and minipiled foundations are used. Geomorphological mapping is cost-effective in helping to locate and avoid the zones of subsidence for future development. 相似文献
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Drainage patterns along passive continental margins are often hypothesised to be the result of drainage disruption following highland uplift and downwarping of the highland flank. Several studies of stream catchments throughout southeast Australia have demonstrated that the opposite tends to be the case in this region because the field evidence favours stream and continental drainage‐divide stability. While significant advances have been made towards understanding this phenomenon in the southeastern corner of the continent, little is known of the evolution of streams and highlands in northeast Australia. Our study examines palaeochannels and fluvial sedimentary units close to the continental drainage divide in six stream catchments along the length of Cape York Peninsula. The results show that four of the catchments (Barron‐Mitchell and Stewart‐Holroyd) have experienced continental divide and drainage stability, whereas the Pascoe‐Wenlock system appears to have experienced westward migration of the continental drainage divide and diversion of the Pascoe River. River diversion here is likely to be a result of the raising of base‐level and flooding of stream channels during the Cretaceous marine transgression and subsequent stream incision by the Pascoe River along structural weaknesses in the underlying strata, following cessation of marine conditions. 相似文献
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以黄河流域的降水、实测径流量、天然径流量、净引水量以及上中游流域的水土保持措施面积等资料为基础,运用经验统计分析法,研究了近50年来黄河入海径流通量的变化及其与降水和人类活动的关系。结果表明,不同的径流来源区降水的变化对入海径流通量的影响是不同的。引水所形成的侧支循环强度的急剧增大,使入海径流通量大幅度下降。上中游大规模水土保持生效后,这一地区的天然年径流有所减少,也导致入海径流通量的减少,入海径流通量与历年梯田、造林、种草面积之间具有一定的负相关。以入海径流通量作为因变量,以净引水量、流域年降水量和上中游梯田、林草面积作为自变量,建立了多元回归方程。 相似文献
11.
大兴安岭北部多年冻土地区路基沉陷研究 总被引：18，自引：5，他引：13
通过对该区４个路段１２个断面为期３ａ的路基沉陷观测并结合线路普查和分析表明,多年冻土路基稳定性与地基的水、热状况密切相关,受自然环境和人为因素的制约。合理布线、保护植被、改善排水、合理确定路基高度以及设置护坡、基底反铺塔头、采用土工聚合材料和无基管涵结构等,是保持该地区路基稳定的有效措施。 相似文献
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昆仑山隧道洞内防排水及衬砌隔热保温层施工技术 总被引：8，自引：0，他引：8
介绍了高原多年冻土世界第一长隧道——昆仑山隧道洞内防排水及衬砌隔热保温层的设计特点, 通过材料性能优选和工艺试验, 选定了适宜于高原多年冻土隧道洞内防排水及衬砌隔热保温层施工的材料, 并制定科学、合理的施工方法和工艺, 确保昆仑山隧道工程质量. 相似文献
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In this study, we documented the Holocene history of a peat plateau at the arctic tree line in northern Québec using stratigraphic and macrofossil analyses to highlight the effects of geomorphic setting in peatland development. Paludification of the site began about 6800 cal yr BP. From 6390 to 4120 cal yr BP, the peatland experienced a series of flooding events. The location of the peatland in a depression bounded by two small lakes likely explains its sensitivity to runoff. The proximity of a large hill bordering the peatland to the south possibly favored the inflow of mineral-laden water. The onset of permafrost aggradation in several parts of the peatland occurred after 3670 cal yr BP. Uplifting of the peatland surface caused by permafrost stopped the flooding. According to radiocarbon dating of the uppermost peat layers, permafrost distribution progressed from the east to the west of the peatland, indicating differential timing for the initiation of permafrost throughout the peatland. Most of the peatland was affected by permafrost growth during the Little Ice Age. Picea mariana macroremains at 6450 cal yr BP indicate that the species was present during the early stages of peatland development, which occurred soon after the sea regression. 相似文献
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我国是个多山国家,隧道工程在公路和铁路建设中占很大比例,涌水问题历来是个难点,多采用排引水方法将水排出施工场地以外,这样会使地下水系统破坏,造成生态失衡,引起环境恶化等生态问题。本文通过雁门关隧道涌水的防治,详细介绍了耐高压厚壁井管与上托盘式止水法[1]的原理、施工工艺及防治效果。该方法不仅可以成功根治水患,保证隧道施工顺利进行,而且可以使其得以充分利用,保护当地生态环境,该涌水防治技术是隧道工程的一大创新,达到了国际领先水平,如推广应用,可实现极高的经济效益和社会效益。 相似文献
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Bruce L. Rhoads 《Environmental Geology》1991,18(2):119-135
The development of irrigation agriculture on valley floors in the southwestern United States has substantially altered natural drainage systems. This study discusses five anthropogenic factors that have altered the hydrologic function of a dryland basin floor in south-central Arizona. These factors are: (1) upstream urbanization and channel entrenchment, (2) dam construction, (3) artificial diversion of drainage, (4) obstruction of flow by transportation routes, and (5) stream channelization. The first two factors have altered hydrologic inputs to the basin floor, the third and fourth factors have changed regional and local patterns of flooding, and the fifth factor has resulted in channel instability and reduced flood attenuation. These five factors, along with a recent increase in the frequency of incursions of tropical moisture into southern Arizona, have enhanced flow variability and the potential for devastating flooding on the basin floor. This research demonstrates the need for basin-wide approaches to stream management in drylands and illustrates the importance of basing management decisions on geomorphic information concerning fluvial forms and processes. 相似文献
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青藏铁路沿线多年冻土分布特征及其对环境变化的响应 总被引：1，自引：0，他引：1
针对青藏高原特殊的自然气候条件,按照地形、地貌把青藏铁路沿线多年冻土分为15个区段,并分别介绍了各个区段多年冻土特征. 结果表明：在外界环境变化,包括全球气候变暖及工程活动的双重效应下,青藏铁路沿线多年冻土及其存在状态发生了极大变化,这些变化主要包括年平均气温升高、多年冻土退化、热融灾害增加、寒区工程病害不断加剧等. 多年冻土及其存在状态发生变化不但导致生态环境恶化,而且对青藏铁路沿寒区工程的安全运营、维护及发展提出新的挑战. 相似文献
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MATTI SEPPALA JAMES GRAY JEAN RICARD 《Boreas: An International Journal of Quaternary Research》1991,20(3):259-285
Morphological and vegetation mapping and stratigraphic studies were carried out on a 60 by 250 m low–centered polygon field on a flood–plain of the Riviére Deception in the continuous permafrost zone of northernmost Ungava. Analyses of grain size, water and ice content, deformation structures, and macrorests were carried out on drill–core samples, up to a maximum depth of 3.19 m, and radiocarbon dates were obtained from several peat horizons. Five different vegetational habits were identified: uplifted banks, ice–wedge fissures, hummocky centres, wet polygon centres, and water ponds. The stratigraphic analyses revealed many sand layers and organic layers, alternating with a few layers of segregated ice. In the raises banks, brown fen peats represent former wet conditions prior to bank uplift. Total ice volumes of the core samples from polygon centres and banks averaged 60%, and were generally in the form of pore ice. Segregated ice was concentrated in ice wedges. The Low gradient of the polygon field and the shallow active layer are responsible for impded drainage. The origins of this isolated low–centred polygon field are discussed in terms of special local terrain conditions. River flooding since glacio–isostatic emergence at 6000 BP repeatedly spread alluvial sands onto the low flood–plain, which thus became progressively built up to its present elevation. Peat layers buried by these alluvial sands have permitted the changing local drainage conditions to be radiocarbon–dated for the last 2600 years for the core sites. Impeded drainage, low winter temperatures, probable thin snow cover, rapid sedimentation of flood–plain sands, and high volumetric ice contents have created the critical thermal regime necessary for repeated frost cracking in a polygonal pattern, with concomitant ice–wedge dev–elopment. Ice wedges developed at least as early as 2200 BP, causing the formation of low banks. Further growth of ice wedges deformed the peat and sand layers on the bank margins and led to the rise of the latter to heights of 0.5 to 1 m above the intervening low wet polygon centres. More water was then collected in the depressions, leading to a transformations of the vegetation cover from mossy heath to sphagnum bog, wet fen, sedge-covered ponds, and eventually in some cases to open-water pools. The stratigraphic evidence suggests that several generations of high banks formed and disappeared and that their position has changed. Deformation by continued ice–wedge growth has been insignificant since 1000 BP, However. A relatively thick surface peat layer also indicates that sand layers have not been contributed to the polygon field by flooding since ? 500 BP. 相似文献
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青藏高原改则地区多年冻土特征 总被引：2，自引：1，他引：1
改则地区地处青藏高原腹地, 气候寒冷干燥, 位于青藏高原大片连续多年冻土南界附近. 2010年"青藏高原多年冻土本底调查"项目在改则地区采用坑探、物探和钻探等多种方法对区域内多年冻土开展了大规模野外考察工作. 根据现场钻探资料和后来的地温观测资料, 并结合坑探和物探资料对改则地区多年冻土特征进行分析, 结果显示: 改则地区多年冻土上限深度在2.6~8.5 m之间, 部分地区存在融化夹层; 多年冻土含冰量在12%~35%之间, 主要为多冰冻土, 而且一般仅在上限附近发育有高含冰量多年冻土; 多年冻土温度普遍较高, 在-1.5~0℃之间; 多年下限深度一般小于60 m, 部分地区甚至在10 m左右; 多年冻土分布的下界海拔高度约为4 700 m, 海拔5 100 m以上区域普遍发育有多年冻土; 区域内多年冻土特征受局地因素影响明显, 特别是与坡向、植被覆盖、岩性和含水量等关系密切; 现场记录资料和后来的测温资料都显示改则地区部分多年冻土正处于退化状态. 相似文献
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以胜利油田A区块特超稠油油藏为目标区块,自主研发了高温高压二维比例物理模型,研究了不同开发阶段水平井蒸汽驱油机理,开展了油藏压力、井底干 度、注汽强度对水平井蒸汽驱的效果影响的研究。物模实验结果显示,蒸汽驱整个过程分为三个阶段：存水回采期、汽驱受效期、蒸汽突破期。存水回采期蒸汽腔向水平方向扩展,以水平驱替方式为主 ;汽驱受效期蒸汽腔向垂向和水平方向扩展,以水平驱替方式为主,纵向泄油为辅;后期蒸汽突破,蒸汽腔继续向上方扩展,以纵向泄油为主,实现油层整体动用。5 MPa时转蒸汽驱的采出程度高于7 MPa时转蒸汽驱的采出程度;蒸汽驱的井底蒸汽干度应不低于0.4,蒸汽干度越高,水平井蒸汽驱的开发效果越好;注汽强度为1.9 t/(d·ha·m)时温度场最为发育。同时,在高压下提高干度可实现水 平井蒸汽驱的有效开发。以上的实验结果较好地指导了胜利油田A区块特超稠油油藏水平井蒸汽驱开发,取得了明显的开发效果,该研究对于类似稠油和超稠油油藏水平井蒸汽驱开发具有重要的指导意义 。 相似文献