波浪作用下粉沙临底输沙特征的试验研究  

Experimental study on the characteristics of silt bottom sediment transport under wave actions

作　　者：朱昊[1,2] 左利钦 陆永军[1] 李寿千[1] 王茂枚[2] 刘菁 ZHU Hao;ZUO Liqin;LU Yongjun;LI Shouqian;WANG Maomei;LIU Jing(The National Key Laboratory of Water Disaster Provention,Nanjing Hydraulic Research Institute,Nanjing 210029,China;Jiangsu Hydraulic Research Institute,Nanjing 210017,China)

机构地区：[1]南京水利科学研究院水灾害防御全国重点实验室,江苏南京210029 [2]江苏省水利科学研究院,江苏南京210017

出　　处：《水科学进展》2023年第4期635-646,共12页Advances in Water Science

基　　金：国家重点研发计划资助项目(2022YFC3204302);国家自然科学基金资助项目(52071221)。

摘　　要：风暴潮及大风天等极端天气下易出现临底高强度输沙,对动力地貌过程、港口航道设施、生态保护等产生深刻影响,开展临底泥沙运动机理研究具有重要的理论价值和工程指导意义。本研究以波浪作用下的粉沙为研究对象,开展波浪水槽输沙试验,构建底部高浓度测沙系统,实现从不动床面到悬沙层的精细测量,观测不同动力环境下的输沙现象。研究结果表明:相对较弱动力条件下的床面存在沙纹,随着动力条件增强,沙纹被冲蚀并出现层移输沙现象;通过不同床面高度含沙量过程的分析,随着波浪的周期性运动,粉沙底部层移运动特征表现为泥面呈现横向摆动的周期性运动,深度越大的泥层摆动幅度越小,并开始出现相位滞后现象;引入移动数和密实度系数,建立了粉沙-沙宽级配范围的层移临界条件下波浪可移动数的计算公式。本研究初步提出了细颗粒泥沙底部运动机制,对进一步研究骤冲骤淤机理具有参考意义。Under extreme weather conditions,such as storm surges or strong winds,high-intensity sand transport at the bed bottom is prone to occur,which has a profound impact on the dynamic geomorphological processes,port and waterway facilities,and ecological protection.It is of significant theoretical and practical engineering importance to conduct research on the mechanisms of sediment transport near the bottom.In this study,silt transport under wave actions was studied via wave flume sediment transport tests conducted in varying dynamic environments.A bottom sediment measurement system with a high sensor density was constructed to collect data from the fixed bed surface to the suspended sediment layer.The results showed that sand ripples on the bed surface developed under relatively weak dynamic conditions.With the increase in dynamic excitation,ripples were eroded and sheet flow occurred.The bottom layer movement of fine sediment,revealed by analyzing the sediment concentration process at different bed heights,was characterized by the silt surface lateral oscillations aligned with the periodic wave motion.The amplitude of the silt layer oscillations decreased with increasing depth and a phase lag arose.The concepts of movement number and compactness coefficient were introduced and a formula for critical sheet flow condition for a siltsand wide gradation range was established.The bottom movement mechanism of fine-grained sediment proposed in this study will form a departing point for further studies of the mechanism of sudden-onset scouring and silting.

关 键 词：粉沙 层移质运动 水槽试验 高含沙层 波浪作用 

分 类 号：TV148[水利工程—水力学及河流动力学]