次降雨条件下坝系流域泥沙淤积过程模拟试验研究

Study on sediment deposition processes under rainfall conditions

了解淤地坝次降雨条件下泥沙淤积特征是研究淤地坝泥沙输移过程的前提和基础。通过室内模拟降雨实验,利用桥沟小流域模型,对次降雨情况下运移的泥沙粒径与淤积深度进行分析。结果表明:在淤积体前缘最末端,淤积深度最高,淤积体上倾斜度为0°,淤积深度随沟道比降沿程减少。在坝前无淤积体位置向上游沿程砂粒占比增高,粉粒占比减少,砂粒占比先增大后减少最后趋于50%左右,粉粒占比先减少后增大最后趋于50%左右。在坝前淤积体未发育位置,颗粒向上游沿程分选结果趋势明显,沿程粒径变大,在淤积体发育完全位置,颗粒沿程分选结果趋势不明显,各粒级泥沙颗粒占比相对稳定。

The grain size and deposition depth of sediment were analyzed by the Qiaogou small watershed model.Results show that the deposition depth is the highest at the end of the front edge of the deposition body,the inclination of the deposition body is 0°,and the deposition depth decreases along the channel slope.In the position without silt in front of the dam,the proportion of sand along the upstream path increases,while the proportion of silt decreases.The proportion of sand increases first,then decreases and finally approaches about 50%,while the proportion of silt decreases first and then increases,finally approach about 50%.In the position in front of the dam where the silting body is not developed,the trend of particle separation along the silting body is obvious upstream,and the particle size along the silting body becomes larger.In the position where the silting body is fully developed,the trend of particle separation along the silting body is not obvious,and the proportion of sediment particles at each particle level is relatively stable.