基岩弯曲河段洪水水流结构的试验研究  

Hydrodynamic of flood in bedrock bend reach: laboratory experiment

作　　者：白玉川[1,2] 李彬[2] 徐海珏[1,2] 冀自青[2] BAI Yuchuan;LI Bin;XU Haijue;JI Ziqing(State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University,Tianjin 300072,China;Institute for Sedimentation on River and Coastal Engineering,Tianjin University,Tianjin 300350,China)

机构地区：[1]天津大学水利工程仿真与安全国家重点实验室,天津300072 [2]天津大学河流泥沙海岸工程研究所,天津300350

出　　处：《水科学进展》2022年第1期102-110,共9页Advances in Water Science

基　　金：国家自然科学基金资助项目(51979185,51879182)。

摘　　要：低坡度基岩弯曲河流在地质构造控制区域广泛存在(床面坡度小于5‰),洪水对基岩弯曲河流的河床淤积与侵蚀具有较大影响,但以往研究对基岩弯曲河流的洪水动力结构认识不足。通过几何概化基岩弯曲河段,考虑Froude相似与边壁粗糙,建立基岩弯曲河道概化模型,分析洪水下的弯道水面线分布、时均流场与湍流结构特性。结果表明:在洪水流量下,弯顶上游出现最小水面横比降、凸岸水流分离、凹岸双环流发育、流速下潜且二次环流强度达到最大,在弯顶下游水面横比降达到最大并出现环流分裂;床面切应力分布于凸岸水流分离以及弯顶上游中心区域,横向动量输移集中于弯顶上游。试验结果为基岩弯曲河道中的床面侵蚀与沿程淤积提供了水动力方面的解释。Low-slope bedrock meandering rivers widely exist in areas controlled by geological structures(the bed slope is less than 5‰). Flood has a great influence on riverbed sedimentation and erosion in bedrock meandering rivers, however, we have a poor understanding of dynamic structure of flood for bedrock meandering rivers. By geometrically generalizing bedrock meandering reaches, considering the Froude similarity and side wall roughness, a generalized model of a bedrock meandering channel is established in order to analyze the water surface profile distribution, time average flow fields and turbulence structure characteristics for bends under flood. The results show that under the flood flow, the minimum water surface transverse gradient, separation of flow on the convex bank, development of double circulation on the concave bank, velocity-dip-phenomenon and maximum secondary circulation intensity are caused at the upstream of the bend apex, and the maximum water surface transverse gradient and circulation splitting are caused at the downstream of the bend apex;the bed shear stress is distributed in the flow separation area at the convex bank as well as the center of the upstream of the bend apex, and the transverse momentum transport is concentrated at the upstream of the bend apex. The experiment results show an explanation in view of hydrodynamics in respect to bed erosion and sedimentation in bedrock meandering rivers.

关 键 词：湍流动能 基岩河流 二次环流 水流分离 常曲率水槽 

分 类 号：TV143[水利工程—水力学及河流动力学]