受堆积体影响的河道3维水流结构试验研究

发布时间：2018-11-19 07:20

【摘要】：在河道中存在堆积体大尺度堆积物时,其对水流结构的影响会较丁坝等小尺度岸边结构物发生明显变化。为更深入地认识堆积体对河道水流结构、河床演变等的影响,通过系列水槽试验研究在堆积体影响下的河道3维水流结构,采用ADV测量堆积体影响河段的3维水流流速。通过分析水位及流速在横向、纵向、垂向上的分布得出:在堆积体作用下,堆积体上游段发生壅水,堆积体段水面降低,下游逐渐恢复天然状态;断面纵向最大流速从堆积体段逐渐偏向右岸,且逐渐向河床底部移动,往下游又逐渐上升并恢复至天然状态。主流受收缩加速影响,越过堆积体后,呈水跃流态。受堆积体挤压流路和水流惯性的影响,主流流速在靠近堆积体略下游位置出现最大值,中层和表层的横向流速亦在堆积体下游出现最大值,底层的横向流速在堆积体中心断面出现最大值。横向流速在堆积体段出现了正负值交替,某一水深处的流速为0,在该水深的上层,水流偏向堆积体岸流动,在该水深的下层,水流偏向右岸流动,上下层水流出现了反向流动,同时垂向流速在堆积体段也出现了正负值交替,表明在试验段水流呈类螺旋流流态。受堆积体作用,水流从表层到床面不等宽收缩,在堆积体段水流呈逆时针螺旋流与纵向水跃交互作用,水流呈复杂的3维状态。
[Abstract]:When there are large scale deposits in the river channel, the influence on the flow structure is more obvious than that on the small scale shoreline structures such as spur dikes. In order to better understand the influence of accumulation body on river flow structure and river bed evolution, a series of flume experiments were conducted to study the 3D flow structure of river channel under the influence of accumulation body. ADV was used to measure the 3-D flow velocity of the channel affected by the accumulation body. By analyzing the horizontal, vertical and vertical distribution of water level and velocity, it is concluded that under the action of the accumulation body, backwater occurs in the upstream section of the accumulation body, the water surface of the accumulation body section decreases, and the downstream gradually returns to its natural state; The longitudinal maximum velocity of the cross section gradually deviates to the right bank and moves to the bottom of the river bed, then rises downstream and returns to the natural state. The main stream is affected by the acceleration of shrinkage, and after crossing the accumulation body, it appears as a water jump flow. Under the influence of the extrusion flow path and the inertia of the water flow, the maximum velocity of the mainstream velocity appeared near the lower reaches of the accumulation body, and the transverse velocity of the middle layer and the surface layer also appeared the maximum value in the lower reaches of the accumulation body. The transverse velocity of the bottom layer appears the maximum value in the central section of the accumulation body. The transverse velocity of flow alternates between positive and negative in the section of the accumulation body, and the velocity of a certain water depth is 0. In the upper layer of the water depth, the flow of water is biased towards the bank of the accumulation body, and in the lower layer of the water depth, the flow is biased to the right bank. There is reverse flow in the upper and lower layers and the vertical velocity alternates positively and negatively in the accumulation section, which indicates that the flow in the test section is spiral-like. Under the action of the accumulation body, the water flow shrinks from the surface to the bed, and the flow in the accumulation section is in the interaction of counterclockwise helical flow and longitudinal hydraulic jump, and the water flow is in a complex three-dimensional state.
【作者单位】：四川大学水力学与山区河流开发保护国家重点实验室;武汉市政设计研究院成都分院;西华大学能源与动力工程学院;
【基金】：国家自然科学基金资助项目(50949057;51409224) 国家科技支撑计划资助项目(2012BAB05B02)
【分类号】：TV143

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