水利学报2023，Vol.54Issue(12)：1485-1495,11.DOI:10.13243/j.cnki.slxb.20230235
河床表层冻融作用下推移质输移特征研究
Freeze-thaw effect of bed surface on bed load transport behaviour
摘要
Abstract
High-latitude rivers generally experience seasonal freeze-thaw process,and the impact of freeze-thaw process on riverbanks dynamics and instability has been widely reported.By contrast,bed-load transport behav-iours in alluvial rivers under the freeze-thaw action is still unknown.As such,two comparative experimental series were executed to isolate the freeze-thaw impact on bed load transport over uniform and non-uniform sediment beds in the present study,the first series focused on the bed load transport under freeze-thaw-free and normal room temperature(20 ℃)condition,and this series is designated as benchmark tests,against which the impact of freeze-thaw action on bedload transport rate and composition can be examined,the second series are the group of comparative experimental tests,within which both uniform and non-uniform sediment beds were worked by sequen-tial events of freeze,thaw,and steady flow at normal room temperature(20 ℃).Our experiments show that bed load transport rates are usually higher for both uniform and non-uniform sediment beds affected by freeze-thaw process if compared with measurements in benchmark tests,accordingly,a ratio ξ of bedload rates measured within freeze-thaw-impacted sediment bed over their equivalents obtained from freeze-thaw-free bed.A comparison be-tween the ratio ξ and normalized shear stress indicates that the ratio ξ is higher(i.e.ξ＞1.0)at lower normalized shear stress and gradually reduced(i.e.ξ→1.0)as normalized shear stress increased.For comparative tests using non-uniform sediment bed,the impact of freeze-thaw action on transported grain size is significant at low flows and gradually attenuated by increasing flow magnitude.These findings are important for enhancing our understanding of alluvial bed stability and evolution in cold regions.关键词
冻融作用/推移质/输沙率/级配组成/河床稳定性Key words
freeze-thaw effect/bed load/transport rate/grain size distribution/bed stability分类
建筑与水利引用本文复制引用
王乐,杨旭博,王大宇,张尚弘,吴雪..河床表层冻融作用下推移质输移特征研究[J].水利学报,2023,54(12):1485-1495,11.基金项目
中国水利水电科学研究院基本科研项目(SE110145B0022021,SE0199A102021) （SE110145B0022021,SE0199A102021）
国家自然科学基金青年科学基金项目(52009041) （52009041）
