复式断面丁坝是常见的航道整治建筑物。通过室内水槽试验开展非淹没复式断面丁坝流速分布规律研究。结果表明①表层合流速高速区主要出现在一级丁坝坝头下游外侧,二级丁坝长度b₂对高速区流速大小及平面分布形态具有明显影响,而弗劳德数Fr只影响高速区流速大小,表层横向流速平面分布接近扇形,最大横流可达试验流速的0.45倍;②横断面上纵向流速高速区位于一级丁坝坝头附近,强横流区位于二级丁坝前缘,均呈带状分布,b₂越大,带宽越小,高速区分布更为集中;③纵剖面上纵向流速最大值出现在丁坝下游靠近水面附近,其沿程位置随b₂的增大而上移,横向流速呈先增大后减小的变化,最大值出现在丁坝附近靠近槽底的部位,强横流区呈枫叶型分布。研究结果可为航道整治工程设计和丁坝水毁保护等提供参考。

Spur dike with compound section is a common structure used in waterway regulation. In this paper, the law of velocity distribution around non-submerged spur dike with compound section is researched via flume experiment, and the results manifest that I) In surface layer, large resultant velocity appears outside the downstream of the first-stage spur dike head; the length (b₂) of the second-stage spur has noticeable impact on the value and morphological distribution of the zone of large resultant velocity whereas Froude number (Fr) only affects the value of velocity; transverse surface velocity distributes in an approximated fan shape, with the maximum value up to 0.45 times of test velocity. (II) In cross-sectional scale, large longitudinal velocity is located in the adjacent of the head of the first-stage spur dike, and intense transverse velocity zone is in the front of the second-stage spur dike, both distributing in a band shape; with the increase of b₂, the band width declines, and the distribution is more concentrated. (III) In longitudinal profile, the maximum longitudinal velocity is found in the downstream of the spur dike near water surface, and its position moves up along with the increase of b₂; while the transverse velocity increases first and then decreases, with its maximum value arising close to the bottom; intense high transverse velocity zone stretches in a maple leaf shape.The research results provide reference for waterway regulation and spur dike protection.