动水条件下泥沙絮凝体粒径变化分析实验研究
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摘要
絮凝体广泛存在于自然界水体中,而在河口海岸动水环境下的黏性细颗粒泥沙的絮凝变化过程是一个重要且有待完善的研究课题。利用长江口北槽现场悬沙样本开展了系统的室内絮凝实验。采用粒径分布与有效粒径两种分析方法,研究了在水流紊动、盐度和悬沙浓度等不同絮凝因子条件作用下对长江口北槽泥沙絮凝体粒径变化的影响。实验结果表明:紊动剪切率对絮凝体粒径作用为先促进后减小,临界值出现在23. 09 s~(-1),此时最大有效粒径为50. 26μm;而悬沙浓度会抑制絮凝体生长;同时长江口北槽悬沙的絮凝饱和盐度要大于高岭土,约为14. 4 ppt。
Flocs are widely found in natural waters,and the flocculation process of viscous fine-grained sediments in the dynamic water environment of the estuary is a significant topic and yet to be studied. Systematic laboratory flocculation experiments were carried out by using suspended sediment samples from the North Channel of the Yangtze Estuary. The effects of different flocculation factors such as turbulent shear rates,salinity and suspended sediment concentration on the particle size change of sediment flocs were analyzed by means of particle size distribution and effective particle size. The experimental results indicate that the floc size under turbulent shear rates is firstly promoted and then reduced,and the critical value appears at 23. 09 s~(-1). The maximum effective particle size is 50. 26 μm,and the suspended sediment concentration inhibits the growth of flocs. At the same time,the flocculation saturation salinity of the sediment in the north channel of the Yangtze River estuary is greater than that of kaolin,which is about 14. 4 ppt.
Flocs are widely found in natural waters,and the flocculation process of viscous fine-grained sediments in the dynamic water environment of the estuary is a significant topic and yet to be studied. Systematic laboratory flocculation experiments were carried out by using suspended sediment samples from the North Channel of the Yangtze Estuary. The effects of different flocculation factors such as turbulent shear rates,salinity and suspended sediment concentration on the particle size change of sediment flocs were analyzed by means of particle size distribution and effective particle size. The experimental results indicate that the floc size under turbulent shear rates is firstly promoted and then reduced,and the critical value appears at 23. 09 s~(-1). The maximum effective particle size is 50. 26 μm,and the suspended sediment concentration inhibits the growth of flocs. At the same time,the flocculation saturation salinity of the sediment in the north channel of the Yangtze River estuary is greater than that of kaolin,which is about 14. 4 ppt.
引文
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16朱中凡,赵明,杨铁笙.水流剪切对细颗粒泥沙絮凝作用实验研究的综述[J].泥沙研究,2010,20(4):73-80Zhu Zhongfan,Zhao Ming,Yang Tiesheng.Experimental research on the flocculation characteristics of cohesive sediment in turbulent flow[J].Journal of Hydroelectric Engineering,2010,20(4):73-80
17 Isaac B,Richard W S,Gail C K,et al.The variability of suspended aggregates on the amazon continental shelf[J].Continental Shelf Research,1997,17(3):267-285
18乔光全,张金凤,张庆河.紊动对黏性泥沙絮凝沉降影响的实验研究[J].天津大学学报,2014(9):811-816Qiao Guangquan,Zhang Jinfeng,Zhang Qinghe,et al.Experimental investigation of the influence of turbulence on the flocculation and settling of cohesive sediment[J].Journal of Tianjin University,2014(9):811-816
19 Eisma D,Li A.Changes in suspended-matter floc size during the tidal cycle in the dollard estuary[J].Netherlands Journal of Sea Research,1993,31:107-117
20 Gratiot N,Manning A J.An experimental investigation of floc characteristics in a diffusive turbulent flow[J].Journal of Coastal Research,2004,20(1):105-113
21 Law B A,Milligan T G,Hill P S,et al.Flocculation on a muddy intertidal flat in Willapa Bay,Washington,part I:a regional survey of the grain size of surficial sediments[J].Continental Shelf Research,2013,60:S136-S144
22 Ma K S,Pierre A C.Colloidal behavior of montmorillonite in the presence of Fe3+ions[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,1999,155(2-3):359-372
23 Winterwerp J C.On the flocculation and settling velocity of estuarine mud[J].Continental Shelf Research,2002,22(9):1339-1360
24 Braithwaite K M,Bowers D G,Nimmo S W,et al.Controls on floc growth in an energetic tidal channel[J].Journal of Geophysical Research:Oceans,2012:117
25 Kumar R G,Strom K B,Keyvani A.Floc properties and settling velocity of San Jacinto estuary mud under variable shear and salinity conditions[J].Continental Shelf Research,2010,30:2067-2081
26 Xia X M,Li Y,Yang H,et al.Observations on the size and settling velocity distributions of suspended sediment in the Pearl River Estuary,China[J].Continental Shelf Research,2004,24:1809-1826
27郭超.黏性泥沙絮凝沉降过程与控制机制研究[D].上海:华东师范大学,2018Guo Chao.Cohesive sediment flocculation and settling processes and the controlling mechanisms[D].Shanghai:East China Normal University,2018
2钱宁,万兆惠.泥沙运动力学[M].北京:科学出版社,2003Qian Ning,Wan Zhaohui.Sediment transport mechanics[M].Beijing:Science Press,2003
3 Winterwerp J C,Manning A J,Martens C,et al.A heuristic formula for turbulence-induced flocculation of cohesive sediment[J].Estuarine,Coastal and Shelf Science,2006,68(1-2):195-207
4严镜海.紊动水流中泥沙沉降速度的初步分析[J].水利水运科学研究,1992(1):25-37Yan Jinhai.Preliminary analysis of sedimentation velocity in turbulent water flow[J].Journal of Nanjing Hydraulic Research Institute,1992(1):25-37
5 Uncles R J,Bale A J,Stephens J A,et al.Observations of floc sizes in a muddy estuary[J].Coastal and Shelf Science,2010,87(2):186-196
6柴朝晖,李昊洁,王茜.黏性泥沙絮凝研究进展[J].长江科学院院报,2016(2):1-9Chai Chaohui,Li Haojie,Wang Qian,et al.Advances in research of cohesive sediment flocculation[J].Journal of Yangtze River Scientific Research Institute,2016(2):1-9
7李秀文,何青.长江口细颗粒泥沙絮凝问题研究综述[J].人民长江,2008,39(6):15-17Li Xiuwen,He Hui.A review of the research on the flocculation of fine particles in the Yangtze Estuary[J].Yangtze River,2008,39(6):15-17
8吕全荣,王效京.长江口细颗粒沉积物的粘土矿物及地球化学特征[J].沉积学报,1985,3(4):141-151Lv Quanrong,Wang Xiaojing.Clay minerals and geochemical characteristics of fine sediments in the Yangtze Estuary[J].Journal of Sedimentation,1985,3(4):141-151
9杨美卿.细泥沙絮凝的微观结构[J].泥沙研究,1986,(1):43-83Yang Meiqin.Fine sediment flocculation microstructure[J].Journal of Sediment Research,1986,(1):43-83
10 Xiao F,Lam K M,Li X Y.PIV characterisation of flocculation dynamics and floc structure in water treatment[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2011,379(1-3):27-35
11 Irene S,Susanne M,Regina M,et al.Impact of shear stress and PH changes on floc size and removal of dissolved organic matter(DOM)[J].Water Research,2012,46(19):6543-6553
12张乃予,周晶晶,王捷.黏性泥沙絮团强度的试验研究综述[J].泥沙研究,2015(5):75-80Zhang Naiyu,Zhou Jingjing,Wang Jie.A review of experimental study on floc strength of cohesive sediment[J].Journal of Sediment Research,2015(5):75-80
13海希,邵宇阳,张健玮,等.高岭土絮凝体粒径变化实验研究[J].水道港口,2018,39(6):709-715Hai Xi,Shao Yuyang,Zhang Jiangwei,et al.Experimental study on change of particle size of kaolin flocs[J].Journal of Waterway and Harbor,2018,39(6):709-715
14陈邦林.长江口南港南槽地区絮凝机理研究:上海城市污水排放背景文献汇编[M].上海:华东师范大学出版社,1988:276-282Chen Banglin.Study on flocculation mechanism in south channel area of south port of Yangtze Estuary:Shanghai Municipal Wastewater Discharge Background Literature[M].Shanghai:East China Normal University Press,1988:276-282
15蒋国俊,张志忠.长江口阳离子浓度与细颗粒泥沙絮凝沉积[J].海洋学报,1995,17(1):76-82Jiang Guojun,Zhang Zhizhong.Cathode concentration in the Yangtze River estuary and flocculation deposition of fine sediment[J].Acta Oceanologica Sinica,1995,17(1):76-82
16朱中凡,赵明,杨铁笙.水流剪切对细颗粒泥沙絮凝作用实验研究的综述[J].泥沙研究,2010,20(4):73-80Zhu Zhongfan,Zhao Ming,Yang Tiesheng.Experimental research on the flocculation characteristics of cohesive sediment in turbulent flow[J].Journal of Hydroelectric Engineering,2010,20(4):73-80
17 Isaac B,Richard W S,Gail C K,et al.The variability of suspended aggregates on the amazon continental shelf[J].Continental Shelf Research,1997,17(3):267-285
18乔光全,张金凤,张庆河.紊动对黏性泥沙絮凝沉降影响的实验研究[J].天津大学学报,2014(9):811-816Qiao Guangquan,Zhang Jinfeng,Zhang Qinghe,et al.Experimental investigation of the influence of turbulence on the flocculation and settling of cohesive sediment[J].Journal of Tianjin University,2014(9):811-816
19 Eisma D,Li A.Changes in suspended-matter floc size during the tidal cycle in the dollard estuary[J].Netherlands Journal of Sea Research,1993,31:107-117
20 Gratiot N,Manning A J.An experimental investigation of floc characteristics in a diffusive turbulent flow[J].Journal of Coastal Research,2004,20(1):105-113
21 Law B A,Milligan T G,Hill P S,et al.Flocculation on a muddy intertidal flat in Willapa Bay,Washington,part I:a regional survey of the grain size of surficial sediments[J].Continental Shelf Research,2013,60:S136-S144
22 Ma K S,Pierre A C.Colloidal behavior of montmorillonite in the presence of Fe3+ions[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,1999,155(2-3):359-372
23 Winterwerp J C.On the flocculation and settling velocity of estuarine mud[J].Continental Shelf Research,2002,22(9):1339-1360
24 Braithwaite K M,Bowers D G,Nimmo S W,et al.Controls on floc growth in an energetic tidal channel[J].Journal of Geophysical Research:Oceans,2012:117
25 Kumar R G,Strom K B,Keyvani A.Floc properties and settling velocity of San Jacinto estuary mud under variable shear and salinity conditions[J].Continental Shelf Research,2010,30:2067-2081
26 Xia X M,Li Y,Yang H,et al.Observations on the size and settling velocity distributions of suspended sediment in the Pearl River Estuary,China[J].Continental Shelf Research,2004,24:1809-1826
27郭超.黏性泥沙絮凝沉降过程与控制机制研究[D].上海:华东师范大学,2018Guo Chao.Cohesive sediment flocculation and settling processes and the controlling mechanisms[D].Shanghai:East China Normal University,2018