人工卵石床面风沙流粒度特征
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摘要
沉积物粒径分布对风沙沉积物的起动、输送和沉降过程十分重要。不同粒径的风沙沉积物空气动力学特征不同,从而导致其起动机理、输送过程和沉降模式不同。因此,粒度可以作为风沙沉积过程的指示器。戈壁是西北地区的一种重要地貌景观,戈壁风沙流是风沙物理研究的内容之一,但目前研究较少,特别是对戈壁风沙流粒度分布的研究,几乎没有报道。本文利用人工卵石床面模拟戈壁地表,对0.25、0.5、1m和2m高度的风沙流粒度特征进行观测,结果表明:沙源、地表状况、风程效应等影响沙粒粒径随高度的变化。沙源近,平均粒径随高度先减小后增加;沙源远,平均粒径随高度增加减小。戈壁表面的不同区域,沙粒粒径级配不同:随高度增加,粗砂、中砂含量降低,细砂、极细砂和粉砂含量增加;随距离增加,中砂含量降低,细砂、极细砂和粉砂含量增加。平均粒径越大,分选越好,偏度越趋于正偏,峰度越趋于变宽。偏度、峰度随分选系数增加而增加。峰度随偏度增加而增加。
Particle size distribution has an important effect on the aeolian material entrainment,transport and deposition.The mechanism of aeolian sediment entrainment,transport distance and mode of deposition are different for different particle size distribution,therefore,the particle size characteristics of aeolian sediment is a good indicator of aeolian sediment.Gobi is an important landscape in the northwest region of China,and aeolian transport in gobi is one of issue in aeolian research.At present,there is little research on gobi aeolian transport,especially on the sand particle size distribution.In this paper,field experiment data in height of 0.25,0.5,1 m and 2 m was used to analyze particle size distribution.The results indicate that aeolian sediment supply,surface situation,wind disturbance control particle size distribution with height.(1)Mean particle size decreases with increasing height in longer distance sediment supply,but in shorter distance,mean particle size decreases with increasing height in certain height and then decreases.(2)Larger particle size impact on gravel surface,wind speed change from sand dunes to gravel surface and wind disturbance causes larger particle reach to higher heights.(3)The larger mean particle size,the better sorting,and skewness become more positive,kurtosis become more leptokurtic.Skewness and kurtosis increase with increasing sorting.Kurtosis increases with increasing skewness.
Particle size distribution has an important effect on the aeolian material entrainment,transport and deposition.The mechanism of aeolian sediment entrainment,transport distance and mode of deposition are different for different particle size distribution,therefore,the particle size characteristics of aeolian sediment is a good indicator of aeolian sediment.Gobi is an important landscape in the northwest region of China,and aeolian transport in gobi is one of issue in aeolian research.At present,there is little research on gobi aeolian transport,especially on the sand particle size distribution.In this paper,field experiment data in height of 0.25,0.5,1 m and 2 m was used to analyze particle size distribution.The results indicate that aeolian sediment supply,surface situation,wind disturbance control particle size distribution with height.(1)Mean particle size decreases with increasing height in longer distance sediment supply,but in shorter distance,mean particle size decreases with increasing height in certain height and then decreases.(2)Larger particle size impact on gravel surface,wind speed change from sand dunes to gravel surface and wind disturbance causes larger particle reach to higher heights.(3)The larger mean particle size,the better sorting,and skewness become more positive,kurtosis become more leptokurtic.Skewness and kurtosis increase with increasing sorting.Kurtosis increases with increasing skewness.
引文
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[14]屈建军,黄宁,拓万全,等.戈壁风沙流结构特性及其意义[J].地球科学进展,2005,20(1):19-23.
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[16]张正偲,董治宝,赵爱国.人工模拟戈壁风沙流与风程效应观测[J].中国科学:地球科学,2011,41(10):1505-1510.
[17]张正偲,董治宝.腾格里沙漠东南缘春季降尘量和粒度特征[J].中国环境科学,2011,31(11):1789-1794.
[18]Leys J,McTainsh G.Soil loss and nutrient decline by wind erosion-cause for concern[J].Australian Journal of Soil and Water Conservation,1994,7(3):30-35.
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[20]Stout J E,Zobeck T M.The Wolfforth field experiment:a wind erosion study[J].Soil Science,1996,161:616-632.
[21]Folk R L,Ward W C.Brazos River bar:a study in the significance of grain size parameters[J].Journal of Sedimentary Petrology,1957,27:3-26.
[22]Dong Z B,Liu X P,Wang H T,et al.The flux profile of a blowing sand cloud:a wind tunnel investigation[J].Geomorphology,2002,49(3/4):219-230.
[23]Dong Z B,Sun H Y,Zhao A G.WITSEG sampler:a segmented sand sampler for wind tunnel test[J].Geomorphology,2004,59(1/4):119-129.
[24]Dong Z B,Wang H T,Liu X P,et al.Velocity profile of a sand cloud blowing over a gravel surface[J].Geomorphology,2002,45(3/4):277-289.
[25]Dong Z B,Lu J F,Man D Q,et al.Equations for the near-surface mass flux density profile of wind-blown sediments[J].Earth Surface Processes and Landforms,2011,36(10):1292-1299.
[26]武建军,罗生虎,闫光虎,等.脉动风场下风沙流结构的数值模拟[J].中国沙漠,2011,31(3):602-606.
[27]曹晞雍,谢莉.风沙流中砂粒拖曳力系数研究[J].中国沙漠,2011,31(3):593-596.
[28]张伟民,王涛,汪万福,等.复杂风况条件下戈壁输沙量变化规律的研究[J].中国沙漠,2011,31(3):543-549.
[29]屈建军,张克存,张伟民,等.几种典型戈壁床面风沙流特性比较[J].中国沙漠,2012,32(2):285-290.
[30]Gillette D A,Herbert G,Stockton P H.Causes of the fetch effect in wind erosion[J].Earth Surface Processes and Landforms,1996,21:641-659.
[2]Chen W N,Yang Z T,Dong Z B.Vertical distribution of grainsize parameters of drifting particles during sand storms in the Taklamakan Desert,Central Asia[J].Physical Geography,1995,16(6):503-523.
[3]Greeley R,Blumberg D G,Williams S H.Field measurements of the flux and speed on wind-blown sand[J].Sedimentology,1996,43:41-52.
[4]Van der Wal D.Grain-size-selective aeolian sand transport on a nourished beach[J].Journal of Coastal Research,2000,16(3):896-908.
[5]Chepil W S,Milne R A.Comparative study of soil drifting in the field and in a wind tunnel[J].Science and Agriculture,1939,19:249-257.
[6]Bagnold R A.The Physics of Blown Sand and Desert Dunes[M].Methuen:London,1954.
[7]Sharp R P.Wind driven sand in Coachella valley,California[J].Bulletin of the Geological Society America,1964,75:785-804.
[8]何清,杨兴华,艾力·买买提明,等.塔克拉玛干沙漠风蚀起沙研究[J].中国沙漠,2011,31(2):315-322.
[9]董玉祥,马骏.输沙量对海岸沙丘表面风沙流中不同粒径沙粒垂向分布的影响[J].中山大学学报(自然科学版),2009,48(3):102-108.
[10]冯大军,倪晋仁,李振山.风沙流中砂粒粒度的垂直和水平分布特征[J].泥沙研究,2008,(5):21-30.
[11]董玉祥,Hesp P A,Namikas S L,等.海岸横向沙脊表面风沙流结构粒度响应的野外观测研究[J].中国沙漠,2008,28(6):1022-1028.
[12]Farrell E J,Sherman D J,Ellis J T,et al.Vertical distribution of grain size for wind blown sand[J].Aeolian Research,2012,7:51-61.
[13]Wang X M,Xia D S,Wang T,et al.Dust sources in arid and semiarid China and southern Mongo impacts of geomorphological setting and surface materials[J].Geomorphology,2008,97:583-600.
[14]屈建军,黄宁,拓万全,等.戈壁风沙流结构特性及其意义[J].地球科学进展,2005,20(1):19-23.
[15]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):368-374.
[16]张正偲,董治宝,赵爱国.人工模拟戈壁风沙流与风程效应观测[J].中国科学:地球科学,2011,41(10):1505-1510.
[17]张正偲,董治宝.腾格里沙漠东南缘春季降尘量和粒度特征[J].中国环境科学,2011,31(11):1789-1794.
[18]Leys J,McTainsh G.Soil loss and nutrient decline by wind erosion-cause for concern[J].Australian Journal of Soil and Water Conservation,1994,7(3):30-35.
[19]Zobeck T M,Fryrear D W.Chemical and physical characteristics of windblown sediment quantities and physical characteristics[J].Transactions of the ASAE,1986,29:1032-1036.
[20]Stout J E,Zobeck T M.The Wolfforth field experiment:a wind erosion study[J].Soil Science,1996,161:616-632.
[21]Folk R L,Ward W C.Brazos River bar:a study in the significance of grain size parameters[J].Journal of Sedimentary Petrology,1957,27:3-26.
[22]Dong Z B,Liu X P,Wang H T,et al.The flux profile of a blowing sand cloud:a wind tunnel investigation[J].Geomorphology,2002,49(3/4):219-230.
[23]Dong Z B,Sun H Y,Zhao A G.WITSEG sampler:a segmented sand sampler for wind tunnel test[J].Geomorphology,2004,59(1/4):119-129.
[24]Dong Z B,Wang H T,Liu X P,et al.Velocity profile of a sand cloud blowing over a gravel surface[J].Geomorphology,2002,45(3/4):277-289.
[25]Dong Z B,Lu J F,Man D Q,et al.Equations for the near-surface mass flux density profile of wind-blown sediments[J].Earth Surface Processes and Landforms,2011,36(10):1292-1299.
[26]武建军,罗生虎,闫光虎,等.脉动风场下风沙流结构的数值模拟[J].中国沙漠,2011,31(3):602-606.
[27]曹晞雍,谢莉.风沙流中砂粒拖曳力系数研究[J].中国沙漠,2011,31(3):593-596.
[28]张伟民,王涛,汪万福,等.复杂风况条件下戈壁输沙量变化规律的研究[J].中国沙漠,2011,31(3):543-549.
[29]屈建军,张克存,张伟民,等.几种典型戈壁床面风沙流特性比较[J].中国沙漠,2012,32(2):285-290.
[30]Gillette D A,Herbert G,Stockton P H.Causes of the fetch effect in wind erosion[J].Earth Surface Processes and Landforms,1996,21:641-659.