山区河流漂石阶梯阵列对水流结构影响的试验研究(摘要)

叶晨，张晨玲，张绍培，杨奉广，王协康

(四川大学水力学与山区河流开发保护国家重点实验室，四川　成都　610065)

【摘　要】　山区河流发育的漂石阵列能显著影响水流结构，增大水流阻力和河床抗冲刷力，稳定了河床和岸坡及挟带泥沙的能力，同时也制约着漂石河床演变过程。基于野外典型漂石河段调查，本文通过水槽试验，探讨了山区河流漂石阶梯阵列内的水动力特征。试验结果研究表明：不同的漂石阶梯排列密度对于水流流速及紊动强度影响明显，尤其在漂石的近尾流区域，且近尾流区域位于漂石下游x<2D的范围内，但漂石阵列内紊动强度，大体呈现先增大后减小趋势，且其峰值点位置相近。并且漂石阵列对近床湍流具有“均匀化”作用，试验资料表明随着漂石排列密度的增加从而显著降低近床区域的湍流强度。

【关键词】　山区河流；漂石阵列；流速分布；紊动强度

基金资助项目：国家自然科学基金项目(51579163、51639007)；国家重点研发计划重点项目(2016YFC0402304-1)。

E-mail:wangxiekang@scu.edu.cn

The Influence of Stepped Boulder Array on Flow Structure in Mountain River

YE Chen,ZHANG Chenling,ZHANG Shaopei,YANG Fengguang,WANG Xiekang

(State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University,Chengdu Sichuan Province　610065)

Abstract:Boulder arrays which are often performed at the riverbed of mountain rivers in southwest region,can greatly affect the water structure and bed transformation.Though increase flow and river erosion resistance,boulder arrays stabilize river boundary and change the ability of the water to carry sediment,but also restricts the evolution of river bed.Based on the field investigation of typical riverbed and open channel experiments,the influence of stepped boulder array on flow structure with shallow depth conditions has been analyzed and discussed.All the experiments were carried out in the fixed bed,which made of 4cm plastic ball as experimental boulders.A side-looking acoustic Doppler velocimeter(ADV)was equipped to record rapidly respond flow movement so as to analysis the field turbulence.From the experimental results,it can be concluded that velocity and turbulent intensity are greatly influenced with different space of stepped boulder arrays,especially in the scale of far-wake region,which is mainly concentrated at x<2D area in the longitudinal impact range of boulder.But within the stepped boulder array,the change of turbulent intensity basically increases first and then decreases and their peak points are both located in similar location.And boulders array having a “uniform” effect on turbulence near the bed,the increase of the space of stepped boulder arrays significantly reduces the turbulence intensity in the near bed.

Key words:Mountain River;Boulder Array;Velocity;Turbulent Intensity