青藏铁路旱桥桥面遮阳对桥下及周边冻土太阳辐射影响

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夏利江, 周国庆, 刘宇翼, 王涛, 阴琪翔. 青藏铁路旱桥桥面遮阳对桥下及周边冻土太阳辐射影响. 地球科学进展, 2014, 29(3): 0380-387[Xia Lijiang, Zhou Guoqing, Liu Yuyi, Wang Tao, Yin Qixiang. Effects of Sunshine-shield of Qinghai-Tibet Railway Land Bridge on the Solar Radiation of Underbridge and Surrounding Permafrost. 地球科学进展, 2014, 29(3): 0380-387] 复制到剪切板

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青藏铁路旱桥桥面遮阳对桥下及周边冻土太阳辐射影响

夏利江^1,², 周国庆^1,³, 刘宇翼³, 王涛³, 阴琪翔³

1.中国矿业大学力学与建筑工程学院,江苏徐州 221008

2.鲁东大学食品工程学院,山东烟台 264025

3.中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州 221008

夏利江(1981-),男,山东潍坊人,讲师,主要从事冻土温度场的研究.E-mail:xlijiang@163.com

修回日期:2014-02-21

基金:国家重点基础研究发展计划项目“冻土工程地基形变机制与基础稳定性评价”(编号:2012CB026103); 国家自然科学基金项目“基于水热耦合分离冰冻胀理论的冻土冻胀力响应研究”(编号:41271096)资助;

摘要

通过分析太阳辐射强度和旱桥桥面影子轨迹随时间的变化规律,建立时间、太阳辐射强度、太阳位置和影子轨迹关系的数学模型,并利用该模型对旱桥桥面遮阳效应进行研究。提出直射率概念表示周边冻土获得的太阳直接辐射能量的比例。研究发现旱桥的高度、走向、桥面宽度等因素对桥下及周边范围冻土的太阳直射率影响很大。随着旱桥高度的增加,桥面遮阳影响范围增大,遮阳中心直射率增大;随着旱桥宽度的增加,桥下及周边冻土的直射率降低;东西走向的旱桥桥下及周边冻土表面直射率非对称性最为明显。旱桥桥面的遮阳可以有效减少桥下及周边冻土的太阳辐射热量,同时也会引起桩基周边冻土表面非均匀太阳辐射受热,这种太阳辐射的非均匀性不可忽视,在旱桥长期稳定性分析中应予以考虑。

关键词: 冻土; 遮阳; 旱桥

中图分类号:P642.14 文献标志码:中图分类号:P642.14;TU445 文献标志码:A 文章编号:1001-8166(2014)03-0380-387 doi:10.11867/j.issn.1001-8166.2014.03.0380 文章编号:中图分类号:P642.14;TU445 文献标志码:A 文章编号:1001-8166(2014)03-0380-387 doi:10.11867/j.issn.1001-8166.2014.03.0380

Effects of Sunshine-shield of Qinghai-Tibet Railway Land Bridge on the Solar Radiation of Underbridge and Surrounding Permafrost

Xia Lijiang^1,², Zhou Guoqing^1,³, Liu Yuyi³, Wang Tao³, Yin Qixiang³

1. School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221008, China

2. School of Food Engineering, Ludong University, Yantai 264025, China

3. State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221008, China

Fund:

Abstract

Based on the change law of solar radiation intensity and shadow of land bridge variation with time, the mathematical model expressing of the relationship among time, solar radiation intensity,solar position and shadow track was established. The effects of the sunshine-shield of land bridge floor were studied using the model. Direct rate concept was proposed to define the proportion of solar direct radiation energy of the surrounding permafrost. The results show that height, direction and width of land bridge are the major influence factors on the solar radiation of underbridge and surrounding permafrost. With the increase of the height, shading scope and direct rate of sunshade center also increase; with the increase of the width, direct rate of the surrounding permafrost decrease; there was obvious asymmetry distribution of permafrost surface direct rate, especially for the east-west bridge. Sunshine-shield of land bridge can effectively reduce the sun radiation heat of the surrounding permafrost and also cause non-uniform distribution of solar radiation on permafrost surface around piles, which should be concerned in the stability estimation of land bridge.

Keyword: Permafrost; Sunshine-shield; Land bridge.

Show Figures

中图分类号:P642.14;TU445 文献标志码:A 文章编号:1001-8166(2014)03-0380-387 doi:10.11867/j.issn.1001-8166.2014.03.0380

1 引言

低纬度和高海拔的结合, 使青藏高原成为地球上太阳辐射最强烈的地区之一。太阳辐射是导致气温和地表温度升高的主要因素之一, 遮挡太阳直接辐射将降低地表温度,改变冻土温度场分布^{[ 1, 2]}。程国栋^{[ 3, 4]}通过观测发现在海拔高度相近的情况下,阴阳坡处的年平均地表温差可达4.6 ℃。赖远明等^{[ 5]}利用有限元模拟了路堤阴阳坡的温度差异。Chou等^{[ 6, 7]}分析路基阴阳坡太阳辐射和温度的差异规律,并指出太阳辐射的差异是形成路基阴阳坡的主要原因。冯文杰等^{[ 8~ 11]}对青藏高原路堤边坡遮阳措施进行现场实测,研究发现遮阳板下地表温度低于天然边坡 6~ 8 ℃。牛富俊等^{[ 12]}对遮阳棚路基试验工程进行实测研究,研究发现棚体内外的日最高气温差值达6.0 ℃,棚体内部及附近土体地温有所降低,多年冻土上限抬升最大幅度达1.0 m。

青藏铁路在高温极不稳定及高温不稳定冻土区修建时, 为解决冻土冻胀和融沉带来的危害问题,保证路基的稳定性, 同时也为保证野生动物迁徙通道的畅通, 采用以桥代路即旱桥的形式^{[ 13, 14]}。旱桥既遮阳又通风能保护冻土,而且有很好的力学稳定性, 是保证高温、高含冰量地段路堤稳定的有力措施^{[ 4, 15]}。旱桥桩基的承载力与其周边冻土温度场密切相关。符进等^{[ 16]}对冻土地区旱桥双桩的温度场进行试验研究发现,旱桥桥面的遮阳会影响桩基周边冻土的温度场分布,阴阳侧桩基冻土上限相差1.0 m左右。在青藏高原冻土退化的背景下,势必对旱桥桩基的长期稳定性产生影响。但是到目前为止, 还没有人系统地对旱桥的遮阳效应做过研究。本文通过对青藏铁路旱桥桥面遮阳机理分析, 找出影响遮阳效应的关键因素,并对旱桥桥下及周边范围冻土表面太阳辐射强度分布规律进行研究。

2 太阳直射强度逐时变化规律

太阳和地球的运动引起到达地面的太阳辐射强度随时间发生变化,因此首先需确定太阳直射辐射强度的逐时变化规律。到达地面(与太阳射线垂直的平面上)太阳直接辐射强度可表示^{[ 17]}为:

(1)

式中: N为自1月1日起算的日序数; P为复合大气透明度系数,简称大气透明度; β_s为太阳高度角,指太阳光线的入射方向和地平面之间的夹角,可由公式(2)计算求得。

式中: φ为地理纬度,以北纬为正; τ 为太阳时角,指某一时刻,日心到地心连线所在的子午圈与地球上观察者所在的子午圈之间的夹角; δ为太阳倾角,表示由地心指向日心的连线与赤道平面的夹角,可由公式(3)计算求得。

大气透明度 P可由公式(4)计算获得:

式中: k_a为大气相对气压,随海拔高度变化,可由公式(5)求得; t_u为林克氏浑浊度系数,随时间和地理位置而变化,可由经验公式(6)求得。

式中: A_tu, B_tu为经验参数, a为海拔高度。

到达地面水平面的逐时太阳直接辐射强度可表示为:

3 旱桥桥面遮阳机理分析

由于地球的自转和绕太阳公转,太阳位置随时间发生变化,旱桥影子轨迹逐时发生变化,周边冻土表面的遮阳情况也在逐时发生变化。周边冻土地面某时刻获得的太阳辐射热量与该时刻太阳辐射强度和遮阳情况密切相关,因此需确定周边冻土表面的遮阳情况与时间之间的相互关系。

3.1 桥面某点的影子运动规律

桥面某点的影子轨迹,可由该点的空间坐标( x₀, y₀, H)、太阳高度角 β_s、太阳方位角 A_s确定。太阳方位角 A_s指太阳光线在地平面上的投影与当地子午线的夹角^{[ 17]},可由公式(8)计算获得。

定义入射角 α,表示太阳光线在地平面上投影与正东方向的夹角。 α与 A_s的关系可表示为:

以原点上方某点(0,0, H)的投影为例,其在某一天内影子的轨迹如图1所示。图1中交点分别表示各个时刻点的影子位置,数字表示该点的时刻。由图1看出,该点的影子的运动轨迹 O'( x, y)随着时间的推移而发生移动,点在一天内的影子运动轨迹相对于 Y轴对称。

空间点 P( x₀, y₀, H)在水平面的投影坐标为( x₀, y₀),其影子轨迹坐标 P'( x, y)可表示为:

式中:上午时刻取负号,下午时刻取正号。

	Figure Option View Download New Window
	图1 投影坐标为原点的影子运动轨迹Fig.1 Original point shadow trajectory

其中太阳高度角 β_s必须满足 β_s>0,即影子轨迹的计算范围为某地某天太阳的日出和日落时间点之间的曲线。

3.2 地面点的遮阳机理

利用空间点在水平面的影子轨迹坐标,可以得到桥面上任意一点的影子运动轨迹。为了进一步分析地面某点是否有太阳辐射,需要进行逆向分析,由影子运动轨迹反推可以获得原点对应的遮阳点在一天内的运动轨迹(图2)。不难发现,图2与图1曲线上的点关于原点对称分布。若满足原点在某天内的任意时间都无阳光照射,则需要在图2所示曲线对应点上方 H处有遮阳措施存在。

	Figure Option View Download New Window
	图2 原点的遮阳点轨迹线Fig.2 Original point sunshade line

对于水平面上一点( x₀, y₀),其遮阳点轨迹坐标可表示为:

因此,分析空间某点是否受光,可通过分析该点在遮阳点轨迹线上对应时刻点上方 H处是否存在遮阳措施获得。

3.3 桥面遮阳机理分析

旱桥桥面可近似认为宽度恒定、高度恒定、无限长的带状水平面。设桥面的宽度为 B,高度为 H。取其桥面中心线上一点在水平面的投影作为原点,取正东方为 X轴正方向,正北方为 Y轴的正方向,建立平面二维坐标系。令该平面轴线与 X轴正方向的夹角为 c,即该桥的走向与正东方夹角为 c。

取某时刻的桥面在地面的垂直投影及其影子轨迹(图3)。图3中实线区表示桥面在地面的投影,虚线区表示该时刻的影子轨迹。由于投影和影子轨迹在任意时刻都是平行的,且在轴线方向上认为无限长,因此对于两者之间的位置关系可以用投影轴线和影子轨迹轴线之间的距离来表示。在直角三角形ΔOO'O″中,O'为O点在该时刻的投影,OO'可由棒影原理得出其值为 H·cot β_s,OO″为带状平面投影和影子轨迹之间的距离,可通过直角三角形内的夹角关系求得。

桥面在水平面的投影范围可表示:

某时刻桥面影子轨迹范围可表示为:

某时刻桥面在水平面的投影与其影子之间的距离 D可表示为:

(16)

4 青藏铁路旱桥遮阳效应评价

在青藏高原多年冻土区,冻土的地温分布受多因素共同影响,其中一个重要的影响因素是表面太阳辐射分布情况^{[ 18~ 20]}。工程现场实测数据表明,冻土表面温差与其表面太阳辐射之差呈现很好的线性关系^{[ 6, 7]}。因此分析旱桥遮阳效应引起的桥下及周边冻土表面的太阳辐射分布规律是十分有必要的。

	Figure Option View Download New Window
	图3 桥面与其影子距离关系Fig.3 Relation between projection and shadow

为了评价旱桥的遮阳效应,提出了直射率 r的概念,其数值表示旱桥周边地面某处某时间段内由于旱桥遮阳效应的太阳直射辐射热量与无遮阳地面太阳直射辐射热量的比值,定义如下:

直射率:

式中: I_s为到达地面水平面的逐时太阳直接辐射强度; I_sz为考虑桥面遮阳影响后的旱桥桥下及周边范围冻土表面的逐时太阳直射辐射热量。当冻土表面在某个时刻未处于桥面影子区域内,此时冻土表面太阳辐射未受到桥面遮阳影响,其辐射强度 I_sz等同于到达地面水平面的逐时太阳直接辐射强度 I_s。当冻土表面在某时刻处于桥面的影子区域内,由于桥面的遮挡作用,冻土表面无太阳直射辐射,此时此处的太阳直射辐射强度 I_sz值为0。

由于青藏高原太阳辐射以直射为主,直射率可反映旱桥桥下及周边冻土表面的太阳辐射分布情况,也可以进一步获得冻土表面温度分布情况。由桥面的遮阳效应引起的桥下及周边冻土表面温降 ΔT与直射率 r之间的关系可表示为:

式中: Q为某时间段内无遮挡水平面的太阳辐射能量;系数 a, b可通过现场实测数据拟合获得。

由旱桥桥面的影子运动轨迹可以看出,在任意时刻影子与桥面平行,直射率相同的点都与桥面平行,因此可通过分析旱桥横断面上的太阳直射率分布情况来反映桥下及周边范围冻土表面太阳辐射状况。

4.1 旱桥周边冻土日平均直射率分布规律

选取春(秋)分、夏至日、冬至日等典型日期,对35°N,海拔4 000 m处旱桥桥面高度、宽度、走向等因素对周边直射率分布情况进行分析,结果如图4~6所示。图4~6中横轴为桥面横断面与地面的交线,坐标值表示周边冻土表面与旱桥轴线在地面投影的距离,坐标值正表示该点处于旱桥左侧,坐标值为负表示该点处于旱桥右侧,纵轴表示直射率。

4.1.1 桥面高度对周边冻土日平均直射率的影响

取桥面宽度为4.2 m,桥面走向30°(与正东方夹角),分别对桥面高度2,5,10,15 m旱桥典型日期的旱桥周边太阳直射率分布情况进行分析(图4)。

	Figure Option View Download New Window
	图4 不同高度旱桥周边冻土日平均直射率(a)春(秋)分;(b)夏至日;(c)冬至日Fig.4 Day average radiation ratio of surrounding permafrost in different bridge heights(a) Eqvinox; (b) Summer solstice; (c) Winter solstice

	Figure Option View Download New Window
	图5 不同宽度旱桥周边冻土日平均直射率(a)春(秋)分;(b)夏至日;(c)冬至日Fig.5 Day average radiation ratio of surrounding permafrost in different bridge widths(a) Eqvinox; (b) Summer solstice; (c) Winter solstice

	Figure Option View Download New Window
	图6 不同走向旱桥周边冻土日平均直射率(a)春(秋)分;(b)夏至日;(c)冬至日Fig.6 Day average radiation ratio of surrounding permafrost in different bridge directions(a) Eqvinox; (b) Summer solstice; (c) Winter solstice

随着旱桥高度的增加,旱桥的遮阳中心逐渐偏离旱桥,遮阳范围增大,但影响强度降低。遮阳中心的偏离距离随着旱桥高度的增加而增加,而且夏至日偏离最小,冬季日偏离最大。

4.1.2 桥面宽度对周边冻土日平均直射率的影响

取桥面高度为5 m,桥面走向30°(与正东方夹角),分别对桥面宽度为2.1,4.2,6.3,10.5 m的旱桥在典型日期的旱桥周边太阳直射率分布情况进行分析。

如图5所示,随着旱桥宽度的增加,旱桥的遮阳范围增大,遮阳中心的直射率降低。遮阳中心的偏离距离随着旱桥高度的增加而增加,而且夏至日偏离最小,冬季日偏离最大。

4.1.3 旱桥走向对周边冻土日平均直射率的影响

取桥面高度为5 m,宽度为4.2 m,分别对旱桥走向与正东方夹角0°,30°,45°,60°,90°旱桥典型日期的旱桥周边太阳直射率分布情况进行分析(图6)。旱桥的走向对周边冻土的日平均直射率影响很大。随着角度的增加,旱桥遮阳中心与旱桥桥面中心的距离逐渐减小,遮阳范围增大,遮阳中心的遮阳强度降低。东西走向旱桥(0°)桥面的遮阳中心的位置随季节发生变化,夏至日与旱桥的距离最小,冬至日距离最大。遮阳中心附近夏至直射率差异性很大。南北走向旱桥(90°)遮阳中心与旱桥中心在地面的投影重合,旱桥附近的直射率呈东西对称分布。

4.2 旱桥周边冻土年平均直射率分布规律

35°N,海拔高度4 000 m旱桥,分别对其高度、宽度、走向等因素对旱桥周边及其桩基附近冻土表面年平均直射率分布情况进行分析(图7~9)。

4.2.1 桥面高度对周边冻土年平均直射率的影响

由图7可以看出,当桥面高度由2 m增大到15 m时,年平均遮阳中心由桥面中心北侧1 m处移至7 m处,随着旱桥桥面高度的增加,遮阳中心区远离旱桥地面垂直投影中心。随着桥面高度的增加桥面遮阳影响范围增大,遮阳中心直射率由10%增大到80%。

对于桩基附近冻土,当桥面高度由2 m增大到15 m时,直射率非均匀性逐渐降低。当桥面高度为2 m时,双桩周边冻土太阳直射率相差达80%。

4.2.2 桥面宽度对周边冻土年平均直射率的影响

由图8可以看出,旱桥桥面宽度由2.1 m增加至10.5 m时,年平均遮阳中心直射率由70%减少至10%,桥面遮阳区域范围增大。对于桩基附近冻土,双桩周边冻土太阳直射率相差30%左右。

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	图7 不同高度旱桥周边冻土年平均直射率Fig.7 Year average radiation ratio in different heights surrounding bridge

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	图8 不同宽度旱桥周边冻土年平均直射率Fig.8 Year average radiation ratio of pile surrounding permafrost in different widths

4.2.3 旱桥走向对周边冻土年平均直射率的影响

由图9可以看出,旱桥的走向对周边冻土的直射率影响很大。随着旱桥走向由东西转到南北走向,年平均遮阳中心与旱桥桥面中心逐渐重合,遮阳中心直射率值由45%增大至65%。当旱桥东西走向时,遮阳中心与旱桥投影中心偏离最大,达2.5 m。

对于桩基附近冻土,当旱桥东西走向时双桩周边冻土南北侧直射率差值达40%。当旱桥南北走向时遮阳中心与旱桥投影中心重合,桩基周边太阳直射率差异较小。

5 结论

通过对青藏铁路旱桥遮阳分析得出以下结论:

(1) 旱桥桥面的高度、宽度、走向和季节变化等因素对周边冻土的太阳直射率影响很大。随着旱桥高度的增加,桥面遮阳影响范围增大,遮阳中心区域直射率增大。随着旱桥宽度的增加,旱桥周边冻土的直射率降低。随着旱桥走向由东西转到南北走向,年平均遮阳中心与旱桥桥面中心逐渐重合,遮阳中心直射率值增大。

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	图9 不同走向旱桥周边冻土年平均直射率Fig.9 Year average radiation ratio of pile surrounding permafrost in different directions

(2) 旱桥桩基附近太阳辐射存在非均匀现象,非均匀性与旱桥高度、走向等因素密切相关。当旱桥高度较低时非均匀性较大。东西走向的旱桥桩基南北侧太阳直射率差异较大,而南北走向差异较小。

(3) 旱桥的遮阳可以有效减少旱桥周边冻土接收的太阳辐射热量,保护冻土。旱桥的遮阳也会引起桩基周边冻土区出现局部非均匀太阳辐射,这将导致旱桥双桩附近温度场非均匀分布,影响到旱桥桩基的承载能力。在青藏高原冻土退化的背景下,这种太阳辐射的非均匀性分布不可忽视,在桩基长期稳定性分析中应予以考虑。

The authors have declared that no competing interests exist.

参考文献

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2012

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1.388

. 2012, 27(11):1 185-1 191

Basic research on the major permafrost projects in the Qinghai-Tibet Plateau

State Key Laboratory of Frozen Soils Engineering, Cold and Arid Environmental and Engineering Research Institute, Chinese Academy of SciencesLanzhou, 730000, China

QinghaiTibet Plateau is representative highaltitude permafrost region on the earth. Along with the operation of Qinghai-Tibet Railway, a new round of economic development in Xizang (Tibet) Autonomous Region has emerged, which need construction of highway, power transmission line and oil/gas pipeline. These proposed projects and already existed projects, including QinghaiTibet Railway, Qinghai-Tibet Highway, Golmud-Lhasa oil product pipeline, and optical cable from Lanzhou to Lhasa, are all located in the QinghaiTibet engineering corridor, which is not wide than 10 km. In this corridor, influences between proposed and existed projects and coupling of multifactors will accelerate the permafrost degradation, and consequently undermine the stability of these projects and ecological environment, especially along with climate change. To meet the national needs, “Basic Research on the Major Permafrost Projects in the Qinghai-Tibet Plateau”, a project of National Basic Research Program of China, was initiated in April, 2012. The aim of this project is to reveal the spacetime revolution of permafrost and permafrostrelated hazards under the scenarios of climate change and intensive engineering activity, construct an evaluation system on stability and service ability of permafrost engineering, and propose a preventative theory and control measures on permafrost engineering hazard, and finally provide scientific guidelines on prearranging plan on permafrost engineering hazard and on construction of major permafrost engineering in the future.

青藏高原是我国乃至世界高海拔多年冻土区的典型代表。伴随着青藏铁路的建成通车，西藏自治区迎来了新一轮经济发展，迫切需要新建高速公路、输变电线路、输油气管道工程等。这些拟建工程与已建的青藏公路、青藏铁路、格拉输油管道、兰西拉光缆等工程均聚集于宽度不足10 km范围内的青藏工程走廊。在这狭长的冻土工程走廊内，已修建或拟建的各种冻土构筑物相互影响，多因素耦合叠加，加速区域内的冻土退化，而冻土融化必将影响到工程的稳定性和生态环境退化。再加上全球气候变化的影响，其变化程度更加剧烈。面对国家需求，国家重点基础研究发展项目“青藏高原重大冻土工程的基础研究”于2012年4月正式启动。该项目旨在揭示气候变化与人类工程活动加剧背景下冻土变化及灾害时空演化规律，建立冻土工程稳定性和服役性能评价体系，提出冻土工程灾害防治理论与控制对策，为冻土构筑物群灾害应急预案和重大冻土工程建设提供科学决策依据。

... 太阳辐射是导致气温和地表温度升高的主要因素之一, 遮挡太阳直接辐射将降低地表温度,改变冻土温度场分布^[1,2] ...

2006

0.0

1.388

. 2006, 21(12):1 304-1 313

Calculating method of global radiation and temperature on the roadbed surface of Qinghai-Xizang railway

1.Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Division of Plateau Atmospheric Physics, Lanzhou 730000,China; 2.Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085,China

The calculating method of global radiation and surface temperature on the roadbed of the Qinghai-Xizang Railway is improved by analyzing the experiment data observed on roadbeds with different railway directions at Wuli. In order to apply this method to all roadbed of the Qinghai-Xizang Railway, a statistical correlaion of calculating parameters with roadbed location and elevation is set up. The long term date series of GAME-Tibet (GAME experiment of engine and water cycle in the Tibetan Plateau which was implemented under the cooperation project between two sides of China and Japan) obtained from the observation site along the Qinghai-Xizang Railway is involved to develop the method.

通过对“青藏铁路乌丽垭口大桥段不同走向路基表面热状况观测试验”资料的分析，改进了已有的青藏铁路边坡表面上的太阳总辐射和表面温度反演方法，并利用中日合作“青藏高原能量水分循环试验”（GAME-Tibet）沿青藏公路长时间序列地面观测资料，建立了地理位置和海拔高度与反演系数之间的统计关系，将该反演方法推广到青藏铁路全线。

... 太阳辐射是导致气温和地表温度升高的主要因素之一, 遮挡太阳直接辐射将降低地表温度,改变冻土温度场分布^[1,2] ...

2003

0.0

... 程国栋^[3,4]通过观测发现在海拔高度相近的情况下,阴阳坡处的年平均地表温差可达4 ...

2005

1.293

0.0

... 程国栋^[3,4]通过观测发现在海拔高度相近的情况下,阴阳坡处的年平均地表温差可达4 ...

... 旱桥既遮阳又通风能保护冻土,而且有很好的力学稳定性, 是保证高温、高含冰量地段路堤稳定的有力措施^[4,15] ...

2004

1.293

0.0

... 赖远明等^[5]利用有限元模拟了路堤阴阳坡的温度差异 ...

2012

1.293

0.0

... Chou等^[6,7]分析路基阴阳坡太阳辐射和温度的差异规律,并指出太阳辐射的差异是形成路基阴阳坡的主要原因 ...

... 工程现场实测数据表明,冻土表面温差与其表面太阳辐射之差呈现很好的线性关系^{[6, 7]} ...

2008

1.293

0.0

... Chou等^[6,7]分析路基阴阳坡太阳辐射和温度的差异规律,并指出太阳辐射的差异是形成路基阴阳坡的主要原因 ...

... 工程现场实测数据表明,冻土表面温差与其表面太阳辐射之差呈现很好的线性关系^{[6, 7]} ...

2011

0.0

1.301

. 2011, 33(4):778-783

Radiation effect of shading boardon embankment side slope on Tibetan Plateau

作为主动保护冻土的典型措施之一的路堤边坡遮阳板护坡措施，对于减少太阳直接辐射到达地表和降低路堤内部温度起到至关重要的作用，阻隔太阳的辐射，减少进入路堤净辐射量和进入地表的热流，降低路堤土体温度. 现场试验结果表明：进入天然路堤边坡表面平均净辐射量为300~350W•m-2，而遮阳板下路堤边坡表面的平均净辐射量为30~45W•m-2，其减少程度平均达到天然总净辐射量的80%~90%以上；在遮阳板护坡措施保护下进入路堤土体热流减少50%~75%；遮阳板下地表温度低于天然边坡6~8℃. 所有监测结果表明，遮阳板护坡措施能够快速有效地减少进入路堤表面的净辐射量和热流值，从而达到降低路堤表面以及土体内部温度，改善路堤土体温度场，在全球变暖的背景下有效延缓了路堤土体温度的抬升速率，保证了路堤稳定安全，确保寒区道路工程的运营畅通.

... 冯文杰等^[8~11]对青藏高原路堤边坡遮阳措施进行现场实测,研究发现遮阳板下地表温度低于天然边坡 6~ 8 ℃ ...

2006

0.0

1.301

. 2006, (1):108-115

An experimental study of the effect of awning along the Qinghai-Tibet railway

State Key Laboratory of Frozen Soil Engineering, CAREERI, CAS, Lanzhou Gansu 730000, China

There are a lot of active measures to protect permafrost adopted in the construction of the Qinghai-Tibet Railway,of which one is awning.The heat preservation effect of the awning can be seen after one year’s awning.After a cycle of cold and warm seasons,an awninged embankment temperature is 3~5 ℃ lower than an ordinary embankment,and the permafrost table ascends 1.0~1.7 m,with an average of 1.1 m,under the berm,the road shoulder and the road center.The protection effect of awning on permafrost is more categorical and obvious than other active measures of permafrost protection.Awning is one of the top-priority choices to actively protect permafrost.

在青藏铁路的施工建设中,许多主动保护冻土的措施已经被采用,遮阳板就是其中之一.遮阳板措施的保温效果在应用只有1 a的时间里面就表现出来,在第1个冷暖季节过后,在遮阳板保护下的路基土体温度就较普通路基低,在路基左路肩部位(阳坡)低出3~5℃;在路基的左右护道、路肩孔和中心孔冻土上限抬升在1.0~1.7 m,平均抬升1.1 m.遮阳板措施对于保护路基冻土效果较其它主动保护冻土措施更快、更明显,是多年冻土区工程建设中主动保护冻土措施的首选措施之一.

2012

1.293

0.0

2003

0.0

0.989

. 2003, 25(5):567-570

Application study of awning to roadway engineering in permafrost regions

1.Environmental and Engineering Research Institute the Chinese Academy of Sciences Lanzhou 730000 China 2.Qinghai Tibet Railway Headquarters of Railways Ministry Golmud 816000 China

Based on the model test data indoors, combined with the numerical calculations and the measured temperatures of air and permafrost,and the test data of roadbed in Fenghuoshan, the protecting effects of the awning on the permafrost table along the road and railway in permafrost regions are compared. The superiority and feasibility of the awning are confirmed. The awning can resist the solar radiation to land surface effectively, and the ground surface temperature can descend 8 ℃～15 ℃, with a maximum difference of 24 ℃.The awning is very important to the safety of roadway.

基于室内试验资料结果,结合数值模拟,以及风火山地区地温资料和风火山实验场现场观测资料,针对遮阳棚对公路铁路沿线路基底下多年冻土的保护作用以及对多年冻土上限的抬升效果进行了对比分析,进一步证实了遮阳棚措施的优越性和可行性。遮阳棚能有效阻挡减少太阳对地面地辐射,使得冻土上限得以较大幅度抬升,对保证道路安全与畅通起着至关重要的作用。

... 冯文杰等^[8~11]对青藏高原路堤边坡遮阳措施进行现场实测,研究发现遮阳板下地表温度低于天然边坡 6~ 8 ℃ ...

2010

0.0

1.301

. 2010, 32(2):325-334

Engineering effects of the sunshine-shield roadbed of the Qinghai-Tibet railway in permafrost regions

太阳辐射是导致气温和地表温度升高的主要因素之一，遮挡了太阳直接辐射后可以有效降低地表温度.基于青藏铁路冻土区遮阳棚路基试验工程监测数据，分析了遮阳棚内外的气温差异和路基地温特征. 结果表明：遮阳棚能够降低棚内气温，监测期间棚内年平均气温低于天然条件下平均气温值0.6℃；监测期内天然条件下近地表0.1~0.3m范围的气温高于1.0m以上气温近1℃，但在棚体内部仅相差约0.3℃；日最高气温值在棚体内外的单日差值达6.0℃，平均气温值在地面0.1m高度处相差4.2℃，1.5m高度处相差2.1℃；在遮阳棚的作用下，棚体内部及附近土体地温有所降低，且多年冻土上限有一定的抬升，抬升最大幅度达1.0m. 监测结果显示了遮阳棚对于保护路基下冻土的良好效果.

... 牛富俊等^[12]对遮阳棚路基试验工程进行实测研究,研究发现棚体内外的日最高气温差值达6 ...

2004

0.0

1.301

. 2004, 26(4):426-434

Three-dimensional temperature character analysis of the land bridge on the Qinghai-Tibet railway

State Key Laboratory of Frozen Soil Engineering, CAREERI, CAS, Lanzhou Gansu 730000, China

Attracted worldwide attention, the Qinghai-Tibet railway is built on the frozen soil regions more than 550 km long, of which about 100 km are built on high-temperature unstable frozen soil. The key to the success or failure of the railway is whether the embankment under it is stable or not. To resolve the problems of frost heaving and the thawing settlement, to insure the stable of the embankment and the unimpeded move of wild animals, the Qinghai-Tibet railway forms a land bridge on the high-temperature unstable frozen soil. However, up to now, nobody has researched the temperature character of the land bridge in cold regions. In this paper, based on differential equations of the problem on temperature field with phase change, a three-dimensional temperature character analysis of the land bridge built in cold regions with high-elevation was made by using the finite element formulae. The analysis shows that in the coming 20 years, the land bridge built on the regions of high-temperature unstable frozen soil could provide cool energy for the frozen soil greatly and protects the frozen soil under it obviously, and then meets the requirement of thermal stable of the frozen soil under it. Moreover, the analysis also proves that to build land bridge for Qinghai-Tibet railway in high-temperature unstable frozen soil regions is indispensable and feasible.

根据带相变瞬态温度场问题的热量平衡控制微分方程,应用有限元法对青藏铁路旱桥的温度特性进行了三维数值分析.结果表明:修建于高温极不稳定冻土地段的旱桥在将来运行20a的过程中对冻土有很好的制冷作用,能很好地保护冻土,保证铁路的运行安全,并且分析和说明了在建的青藏铁路在高温极不稳定冻土地段的采用旱桥的形式是可行的和必要的.

... 青藏铁路在高温极不稳定及高温不稳定冻土区修建时, 为解决冻土冻胀和融沉带来的危害问题,保证路基的稳定性, 同时也为保证野生动物迁徙通道的畅通, 采用以桥代路即旱桥的形式^[13,14] ...

2009

1.293

0.0

2005

0.0

... 旱桥既遮阳又通风能保护冻土,而且有很好的力学稳定性, 是保证高温、高含冰量地段路堤稳定的有力措施^[4,15] ...

2013

0.0

0.4736

... 符进等^[16]对冻土地区旱桥双桩的温度场进行试验研究发现,旱桥桥面的遮阳会影响桩基周边冻土的温度场分布,阴阳侧桩基冻土上限相差1 ...

2010

0.0

0.465

. 2010, (3):458-463

Reversing effect of building lighting technology based on shadow track line

根据"立竿见影"现象及竿影日照图的原理,分析影子的形成原理和影子随时间的变化规律,建立了时间、太阳位置和影子轨迹关系的数学模型,利用影子轨迹图分别推导出求解建筑物朝向、间距、采光时间的数学公式.设计算法通过Visual Basic和Visual Lisp编程,研制计算机反求实验平台,构建利用竿影轨迹图反求建筑采光效果的方法.

... 到达地面(与太阳射线垂直的平面上)太阳直接辐射强度可表示^[17]为: ...

... 太阳方位角A_s指太阳光线在地平面上的投影与当地子午线的夹角^[17],可由公式(8)计算获得 ...

2011

0.0

1.388

. 2011, 26(11):1 217-1 224

Research progress on surface albedo under global change

Xiao Dengpan

(肖登攀) , (陶福禄) , Moiwo Juana P

1.Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing100101, China; 2. Graduate University of Chinese Academy of Sciences, Beijing100049, China

Surface albedo is a critical consideration for energy balance at the land-air interface. It determines the allocation of radiant energy between the earth′s surface and atmosphere. Changes in surface albedo affect the energy balance of land-air system, which could in turn lead to climate change. Land Use/Cover Change (LUCC) is an important element of global climate change. LUCC affects surface albedo, and thus climate change. Surface albedo is controlled by solar elevation angle, land surface nature, soil moisture, weather condition, etc. This paper presents an in-depth review of the driving factors of surface albedo. Conventional observations of surface albedo are point-based, and therefore have limited spatial representation. On the other hand, surface albedo retrieved by Remote Sensing (RS) could have a large spatial representation. However, RS-driven surface albedo needs validation by ground-truth observations. Hence this paper reviews and epitomizes observational and RS-based analyses surface albedo. It also summarizes research progress in surface albedo in relation to global climate. Moreover, this review highlights the strengths, weaknesses and future directions of surfacealbedo/climate-change research. The points documented herein could profoundly augment current understanding about global climate change and related driving factors.

地表反照率表征地球表面对太阳辐射的反射能力，决定着地表与大气之间辐射能量的分配过程，是影响地球气候系统的关键变量。在全球变化日益突出的今天，地表反照率与全球变化的相互影响机制已经成为地球科学研究领域的热点问题之一。地表反照率的细微变化，会影响到地气系统的能量收支平衡，进而引起区域以至全球气候变化。详细介绍地表反照率影响因素、研究方法等方面的最新研究进展，并从全球变化的角度阐述地表反照率的研究动态及其研究方向。

... 4 青藏铁路旱桥遮阳效应评价在青藏高原多年冻土区,冻土的地温分布受多因素共同影响,其中一个重要的影响因素是表面太阳辐射分布情况^[18~20] ...

2013

0.0

1.388

. 2013, 28(4):407-419

Studies of Earth surface processes: Progress and prospect

1.State Key Laboratory of Cryospheric Science, Cold & Arid Regions Environmental & Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; 2.State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing100101, China; 3.Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources,Yangling712100, China; 4.State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumchi830011,China; 5.Institute of Soil Sciences, Chinese Academy of Sciences, Nanjing210008,China; 6.Laboratory of Remote Sensing and Geospatial Sciences, Cold & Arid Regions Environmental & Engineering Research Institute, Chinese Academy of Sciences, Lanzhou730000, China

The Earth (land) surface processes are very complex. The current status of the study of the land surface processes is reviewed, and some concepts and connotations are discussed. Based on the analysis of the study focused on single-factor and on multifactor Earth surface processes, respectively, the characteristics of the study of the Earth surface processes are discussed from integration of research content, international cooperation of multinational, regional characteristics focusing on outstanding problems in the area, the dynamics of the core of the earth surface processes change, and the diversity of research methods. The overall prospects of the study of the Earth surface process are summarized, includeing that the studies of the Earth surface processes will be the focus and hot topics of future study of Earth system science, the studies of key processes controlling climate change are the important issue of study of the Earth surface processes, the studies of the interfaces between different components within the Earth surface system are the important entry points, the coupling study of natural processes and human processes will be important direction, advanced technology and facilities have increasingly prominent supporting role, and networking and cross-integration research will be more important organizing mode in the study of earth surface processes. The opportunities of the studies on the Earth surface processes in China are pointed out from the international scientific research trends, national needs, information and technologies. The challenges facing the study of the Earth surface processes are discussed from cross study of multidisciplinary, quantities and coupling study of natural and human processes, theory and method of earth surface systems study, three-dimensional observation-data assimilation-model simulation-decision support integration.

地表过程复杂多样、涉及广泛。针对当前地表过程研究现状，从地球系统科学和全球变化的视角讨论了与地表过程相关的一些概念及研究内涵。在分析单要素地表过程和多要素地表过程的基础上，从研究内容的综合性、多国合作的国际性、针对区域突出问题的区域性、以过程变化为核心的动态性及研究方法的多样性等方面论述了地表过程研究的特点,总结性地给出了国内外研究的总体趋势。在上述分析基础上，进一步从国际科学发展趋势、国家需要和信息、技术等方面分析了中国地表过程研究所面临的机遇；从多学科交叉、自然与人文过程的定量与有机耦合等方面讨论了地表过程研究所面临的挑战。

2013

0.0

1.388

. 2013, 28(6):695-702

Distribution of thermokarst lakes and its thermal influence on permafrost along Qinghai-Tibet highway

1.State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000，China; 2.The College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, China

The occurrence of thermokarst lake is an indicator implying the permafrost warming. A study of thermokarst lake and their thermal effect will become an important basic work that responds to the permafrost hazards induced by the climate changes and the anthropogenic activities on the QinghaiTibet Plateau. Based on SPOT-5 satellite image data, we interpreted and obtained the area and quantity of thermokarst lakes from Chumaerhe to Fenghuoshan Mountain section along the Qinghai-Tibet Highway under the ArcGIS platform in this paper. The result shows that these thermokarst lakes have mainly spread in Chumaerhe High Plains and Beiluhe Basin and approximately 80% lakes have been developing in rich-ice permafrost regions. The thermokarst lake influences the permafrost through downward and lateral heat transfer. The downward heat transfer accelerates the thawing of permafrost and the formation of an open-talik, the lateral heat erosion will cause the permafrost warming at lakeshore and expand the scope of the heat-affected. The modeled result of a typical thermokarst lake in Beiluhe Basin shows that the lake has always released the heat to lakeshore in a whole year. If the thermokarst lake is close to the roadbed, it will cause influence on the stability of roadbed, especially the lateral thermal erosion often leads to the temperature increases of frozen soil subgrade and induces the embankment disease.

热喀斯特湖的出现和发育是多年冻土变暖的指示器，研究热喀斯特湖发育及其热效应是应对青藏高原气候变化和人类活动诱发冻土灾害的基础工作。基于SPOT5卫星影像资料，在ArcGIS平台下解译遥感影像，获取了青藏公路沿线楚玛尔河至风火山段热喀斯特湖的数量和分布特征，这些热喀斯特湖以楚玛尔河高平原和北麓河盆地为主要分布区，且80％发育于高含冰量多年冻土区。热喀斯特湖通过竖向和侧向2种传热方式影响多年冻土，竖向传热会造成其下部多年冻土融穿，侧向传热会造成湖岸多年冻土增温，扩大热影响范围。通过北麓河地区一典型热喀斯特湖的数值计算，湖全年都在向湖岸放热。当热喀斯特湖离路基较近，将会对公路产生潜在或者直接的危害，其侧向热侵蚀往往会导致冻土路基温度升高，诱发路基病害。

... 4 青藏铁路旱桥遮阳效应评价在青藏高原多年冻土区,冻土的地温分布受多因素共同影响,其中一个重要的影响因素是表面太阳辐射分布情况^[18~20] ...