不同砾石盖度戈壁床面动力学特征研究
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摘要
利用野外车载移动式风洞,对莫高窟顶不同砾石盖度戈壁床面的动力学特征进行了实地模拟实验。结果表明:砾石盖度直接决定戈壁床面的粗糙元数量和分布状况,进而影响近地表风速廓线、摩阻速度、床面粗糙度和剪切力;随着风洞进口指示风速的增加,摩阻速度呈线性递增,而动力学粗糙度在波动中呈下降趋势;相同高度,随着砾石盖度的增加,近地表风速逐渐降低,而摩阻速度、动力学粗糙度和剪切力呈线性增加;当床面盖度增加至35%时,动力学粗糙度达到0.30 cm,摩阻速度相应提高到0.93 cm/s,床面剪切力增加至1.11 N/cm。
In order to understand the dynamic properties of Gobi surface,some wind tunnel experiments were conducted on the Gobi surface with different gravel coverage on the top of the Mogao Grottoes in Dunhuang,Gansu Province,China.The study results showed that gravel coverage of Gobi surface affected directly the amount and distribution of roughness elements,such as the wind speed profile,friction velocity,roughness degree and shear stress.Friction velocity was increased in a linear way with the increase of wind speed in the wind tunnel,but the dynamic roughness was decreased in a fluctuation way.Wind speed near Gobi surface was gradually decreased with the increase of gravel coverage,but the friction velocity,dynamic roughness and shear stress were increased in a linear way.When the gravel coverage was increased to 35%,the dynamic roughness,friction velocity and shear stress on the Gobi surface were 0.30 cm,0.93 cm/s and 1.11 N/cm respectively.The results in this paper can be used to guide the design of sand-control structures both in our study area and other Gobi regions where it suffers from windblown sand.
In order to understand the dynamic properties of Gobi surface,some wind tunnel experiments were conducted on the Gobi surface with different gravel coverage on the top of the Mogao Grottoes in Dunhuang,Gansu Province,China.The study results showed that gravel coverage of Gobi surface affected directly the amount and distribution of roughness elements,such as the wind speed profile,friction velocity,roughness degree and shear stress.Friction velocity was increased in a linear way with the increase of wind speed in the wind tunnel,but the dynamic roughness was decreased in a fluctuation way.Wind speed near Gobi surface was gradually decreased with the increase of gravel coverage,but the friction velocity,dynamic roughness and shear stress were increased in a linear way.When the gravel coverage was increased to 35%,the dynamic roughness,friction velocity and shear stress on the Gobi surface were 0.30 cm,0.93 cm/s and 1.11 N/cm respectively.The results in this paper can be used to guide the design of sand-control structures both in our study area and other Gobi regions where it suffers from windblown sand.
引文
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(3)Huang N,Zhen X J.A laboratory test of the electrification phenom-enon in wind-blown sand flux(J).Chinese Science Bulletin,2001,46(5):417-420.
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(5)Zou Xueyong,Liu Yuzhang,Dong Guangrong.Tentative calculationof wind-sand current energy(J).Chinese Science Bulletin,1994,39(12):1 016-1 020.
(6)屈建军,黄宁,拓万全,等.戈壁风沙流结构特征及其意义(J).地球科学进展,2005,20(1):19-23.(Qu Jianjun,Huang Ning,Ta Wanquan,et al.Structural characteristics of Gobi sand-drift andits significance(J).Advance in Earth Science,2005,20(1):19-23.)
(7)Zhang K C,Qu J J,Zu R P.Characteristics of wind blown sand onGobi/mobile sand surface(J).Environmental Geology,2008,54:411-416.
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(9)Zhang W M,Wang T,Wang W F,et al.The Gobi sand stream andits control over the top surface of the Mogao Grottoes,China(J).Bulletin of Engineering Geology and the Environment,2004,63:261-269.
(10)Dong Z B,Qu J J,Liu X P,et al.Experimental investigation of thedrag coefficients of gobi surfaces(J).Science in China:Series D,2002,45(7):609-615.
(11)刘小平,董治宝.空气动力学粗糙度的物理与实践意义(J).中国沙漠,2003,23(4):337-346.(Liu Xiaoping,Dong Zhibao.Review of aerodynamic roughness length(J).Journal of Desert Re-search,2003,23(4):337-346.)
(12)Marshall J K.Measurements in roughness arrays of varying densityand distribution(J).Agricultural Meteorology,1971,8:269-296.
(13)Raupach M R.Drag and drag partition on rough surfaces(J).Boundary-layer Meteorology,1992,60:375-395.
(14)王涛,张伟民,汪万福,等.莫高窟窟顶戈壁防护带阻截和输导功能研究(J).中国沙漠,2004,24(2):187-190.(Wang Tao,Zhang Weimin,Wang Wanfu,et al.Study on the function of arrest-ing and transporting sands of Gobi preventing system over the top ofMogao Grottoes(J).Journal of Desert Research,2004,24(2):187-190.)
(15)张伟民,汪万福,李志刚,等.敦煌莫高窟顶几种典型床面蚀积量变化过程的初步观测(J).中国沙漠,2008,28(6):1039-1 045.(Zhang Weimin,Wang Wanfu,Li Zhigang,et al.Process ofwind erosion and deposition on the typical beds in the atop ofMogao Grottoes,Dunhuang(J).Journal of Desert Research,2008,28(6):1 039-1 045.)
(16)薛娴,张伟民,王涛.戈壁砾石防护效应的风洞实验与野外观测结果:以敦煌莫高窟顶戈壁的风蚀防护为例(J).地理学报,2000,55(3):375-383.(Xue Xian,Zhang Weimin,Wang Tao.Wind tunnel experiments on the effects of gravel protection andproblems of field surveys(J).Acta Geographica Sinica,2000,55(3):375-383.)
(17)吴正.风沙地貌学(M).北京:科学出版社,1987:59.(WuZheng.Aeolian Geomorphology(M).Beijing:Science Press,1987:59.)
(18)刘小平,董治宝,王训明.固定沙质床面的空气动力学粗糙度(J).中国沙漠,2003,23(2):111-117.(Liu Xiaoping,DongZhibao,Wang Xunming.Aerodynamic roughness of fixed sandybeds(J).Journal of Desert Research,2003,23(2):111-117.)
(19)Bagnold R A.The Physics of Blown Sand Desert Dunes(M).Lon-don:Methuen,1941:57-75.
(20)Iversen J D,White B R.Saltation threshold on Earth,Mars and Ve-nus(J).Sedimentology,1982,29:111-119.
(21)梅凡民,张小曳,张承中,等.巴丹吉林沙漠戈壁地区不同地表覆盖类型下表土的平均起动摩阻速度(J).过程工程学报,2004,4(增刊):754-759.(Mei Fanmin,Zhang Xiaoye,ZhangChengzhong,et al.The mean threshold wind friction velocities ofsurface soils with various land cover types in the Badain Jaran Des-er(t J).The Chinese Journal of Process Engineering,2004,4(Sup-pl.):754-759.)
(2)王涛,陈广庭.中国的沙漠戈壁(M).上海:上海科学技术文献出版社,2008:216-217.(Wang Tao,Chen Guangting.Desert andGobi in China(M).Shanghai:Shanghai Scientific and Technologi-cal Literature Publishing House,2008:216-217.)
(3)Huang N,Zhen X J.A laboratory test of the electrification phenom-enon in wind-blown sand flux(J).Chinese Science Bulletin,2001,46(5):417-420.
(4)邹学勇,董光荣,王周龙.戈壁风沙流若干特征研究(J).中国沙漠,1995,15(4):368-373.(Zou Xueyong,Dong Guangrong,Wang Zhoulong.A study on some characters of drifting sand flux o-ver Gobi(J).Journal of Desert Research,1995,15(4):368-373.)
(5)Zou Xueyong,Liu Yuzhang,Dong Guangrong.Tentative calculationof wind-sand current energy(J).Chinese Science Bulletin,1994,39(12):1 016-1 020.
(6)屈建军,黄宁,拓万全,等.戈壁风沙流结构特征及其意义(J).地球科学进展,2005,20(1):19-23.(Qu Jianjun,Huang Ning,Ta Wanquan,et al.Structural characteristics of Gobi sand-drift andits significance(J).Advance in Earth Science,2005,20(1):19-23.)
(7)Zhang K C,Qu J J,Zu R P.Characteristics of wind blown sand onGobi/mobile sand surface(J).Environmental Geology,2008,54:411-416.
(8)朱震达,吴正,刘恕,等.中国沙漠概论(M).北京:科学出版社,1980:79.(Zhu Zhenda,Wu Zheng,Liu Shu,et al.Introductionto the Desert in China(M).Beijing:Science Press,1980:79.)
(9)Zhang W M,Wang T,Wang W F,et al.The Gobi sand stream andits control over the top surface of the Mogao Grottoes,China(J).Bulletin of Engineering Geology and the Environment,2004,63:261-269.
(10)Dong Z B,Qu J J,Liu X P,et al.Experimental investigation of thedrag coefficients of gobi surfaces(J).Science in China:Series D,2002,45(7):609-615.
(11)刘小平,董治宝.空气动力学粗糙度的物理与实践意义(J).中国沙漠,2003,23(4):337-346.(Liu Xiaoping,Dong Zhibao.Review of aerodynamic roughness length(J).Journal of Desert Re-search,2003,23(4):337-346.)
(12)Marshall J K.Measurements in roughness arrays of varying densityand distribution(J).Agricultural Meteorology,1971,8:269-296.
(13)Raupach M R.Drag and drag partition on rough surfaces(J).Boundary-layer Meteorology,1992,60:375-395.
(14)王涛,张伟民,汪万福,等.莫高窟窟顶戈壁防护带阻截和输导功能研究(J).中国沙漠,2004,24(2):187-190.(Wang Tao,Zhang Weimin,Wang Wanfu,et al.Study on the function of arrest-ing and transporting sands of Gobi preventing system over the top ofMogao Grottoes(J).Journal of Desert Research,2004,24(2):187-190.)
(15)张伟民,汪万福,李志刚,等.敦煌莫高窟顶几种典型床面蚀积量变化过程的初步观测(J).中国沙漠,2008,28(6):1039-1 045.(Zhang Weimin,Wang Wanfu,Li Zhigang,et al.Process ofwind erosion and deposition on the typical beds in the atop ofMogao Grottoes,Dunhuang(J).Journal of Desert Research,2008,28(6):1 039-1 045.)
(16)薛娴,张伟民,王涛.戈壁砾石防护效应的风洞实验与野外观测结果:以敦煌莫高窟顶戈壁的风蚀防护为例(J).地理学报,2000,55(3):375-383.(Xue Xian,Zhang Weimin,Wang Tao.Wind tunnel experiments on the effects of gravel protection andproblems of field surveys(J).Acta Geographica Sinica,2000,55(3):375-383.)
(17)吴正.风沙地貌学(M).北京:科学出版社,1987:59.(WuZheng.Aeolian Geomorphology(M).Beijing:Science Press,1987:59.)
(18)刘小平,董治宝,王训明.固定沙质床面的空气动力学粗糙度(J).中国沙漠,2003,23(2):111-117.(Liu Xiaoping,DongZhibao,Wang Xunming.Aerodynamic roughness of fixed sandybeds(J).Journal of Desert Research,2003,23(2):111-117.)
(19)Bagnold R A.The Physics of Blown Sand Desert Dunes(M).Lon-don:Methuen,1941:57-75.
(20)Iversen J D,White B R.Saltation threshold on Earth,Mars and Ve-nus(J).Sedimentology,1982,29:111-119.
(21)梅凡民,张小曳,张承中,等.巴丹吉林沙漠戈壁地区不同地表覆盖类型下表土的平均起动摩阻速度(J).过程工程学报,2004,4(增刊):754-759.(Mei Fanmin,Zhang Xiaoye,ZhangChengzhong,et al.The mean threshold wind friction velocities ofsurface soils with various land cover types in the Badain Jaran Des-er(t J).The Chinese Journal of Process Engineering,2004,4(Sup-pl.):754-759.)