淹没式矮堰基础冲刷时空演变特性及比尺效应研究

Local scour depth around submerged weirs is one of the most important engineering design parameters, which significantly affects the stability and safety of the structure. The equilibrium scour depth around submerged weirs has been extensively investigated in the past, while studies on time-spatial evolution of scour hole and scale effects on scour process are still limited. This project will investigate the time-spatial evolution and scale effects of scour process around submerged weirs. On the basis of experimental data, the relationship between frequency of approaching bedforms and the fluctuation frequency of scour depths around submerged weirs during scour process will be quantified; an empirical relationship between time development of live-bed scour depth around submerged weirs and dependent factors of scour process will be developed. According to the results of numerical simulation, the scale effects on turbulent flow and scour process around submerged weirs will be discussed. The findings and results of this project will obtain a better understanding of the scour mechanism around submerged weirs, and provide scientific basis for the scour design and maintenance of submerged weirs in the future.

淹没式矮堰基础附近冲刷坑的深度是矮堰设计的重要参数，关系到建筑物的稳定与安全。已有研究多针对淹没式矮堰基础附近的最终平衡冲刷深度的预测，对于淹没式矮堰基础冲刷时空演变过程和冲刷比尺效应的认识却较为有限。本项目将对淹没式矮堰基础冲刷的时空演变特性与比尺效应展开研究，首先采用室内物理模型试验的方法探讨沙波输移对矮堰基础冲刷过程以及最终冲刷坑形态的影响，建立冲刷历时过程模型，再结合数值模拟结果分析冲刷过程和流场演变的比尺效应。研究将量化淹没式矮堰基础冲刷过程中堰前沙波（沙纹）频率与冲坑深度振动频率之间的关系，阐明淹没式矮堰附近冲坑深度历时变化过程与各冲刷因素间的关系，总结比尺效应对紊动流场和冲刷过程预测所带来的影响。项目研究成果将加强对淹没式矮堰基础冲刷机理的认识，并为实际工程情况下淹没式矮堰的冲刷防护设计和工程维护提供科学依据。

淹没式矮堰基础附近冲刷坑的深度是矮堰设计的重要参数，关系到建筑物的稳定与安全。已有研究多针对淹没式矮堰基础附近的最终平衡冲刷深度的预测，对于淹没式矮堰基础冲刷时空演变过程和冲刷比尺效应的认识却较为有限。本项目对淹没式矮堰基础冲刷的时空演变特性与比尺效应展开研究，首先采用室内物理模型试验的方法探讨沙波输移对矮堰基础冲刷过程以及最终冲刷坑形态的影响，建立冲刷历时过程模型，再结合数值模拟结果分析冲刷过程和流场演变的比尺效应。研究量化了淹没式矮堰基础冲刷过程中堰前沙波频率与冲坑深度振动频率之间的关系，阐明了淹没式矮堰附近冲坑深度历时变化过程与各冲刷因素间的关系，总结了比尺效应对紊动流场和冲刷过程预测所带来的影响。项目研究成果加强了对淹没式矮堰基础冲刷机理的认识，并为实际工程情况下淹没式矮堰的冲刷防护设计和工程维护提供了科学依据。