浮堤局部三维水流特性试验研究

Experimental study on the 3D flow structures around the floating dike

  • 摘要: 浮堤相较于传统坝体,具有对河流泥沙输移影响较小、对来水来沙条件适应性较好、对原有河床及生态环境影响较小等优点,但对浮堤局部三维水流结构相关认识的严重缺乏制约了浮堤在河道治理中的应用。通过水槽试验研究浮堤局部三维水流特性及其几何尺寸对水流结构的影响。结果表明:(1)表面水流经过浮堤后向对岸偏转,浮堤下游产生回流,且回流处的垂向紊动强度与雷诺应力绝对值较大;(2)浮堤的挡水作用使过水断面面积减小,浮堤上游水流缓慢,而浮堤下方和右侧水流流速较大;(3)当浮堤淹没深度或长度增加时,浮堤下游回流的垂向或横向尺度相应增大,非接岸侧水体流速均明显增大;(4)当浮堤厚度增加时,水流结构呈非单调变化,表现为当浮堤厚度小于某一值时,浮堤厚度越大,回流横向尺度越大,超过该厚度后回流横向尺度减小。研究结果可为浮堤在河道整治工作中的推广应用提供参考。

     

    Abstract: Compared to dikes constructed on the river bed, floating dikes have the advantages over the spur dikes of minor influence to the riverine sediment transport, bed topography, ecosystem and good capability of adaptation to the fluvial conditions. Yet, floating dikes have not been applied to the river regulation, due to the limited understanding of the 3D flow structures around floating dikes. Our experimental studies were conducted to investigate the effects of the floating dike on the 3D flow structures around it. Results showed that after placing the floating dike, the surface water flow deflected into the other side of the flume, and circumfluence occurred right downstream of the dike, where both the vertical turbulent intensity and the absolute value of Reynolds stress were relatively large. Due to impediment effects of the dike, cross-sectional area decreased, causing the increase of flow velocity below and beside the dike and decrease of flow velocity upstream of it. Increase of the immersed depth or the dike length resulted in the increases of flow velocity beside the dike as well as the vertical or lateral scale of the circumfluence, while increasing the dike thickness led to the weakening, or even disappearing of the circumfluence.

     

/

返回文章
返回