等阻力树杈型冲沙管道的试验研究

多沙河流上修建的水库必然要面对泥沙淤积问题,合理科学的库容恢复和保持措施对于水库综合效益的正常发挥具有重要意义。排沙廊道是一种一次建设、可持续使用的排沙设施,但传统排沙廊道中各进口为顺序排列,不同部位进口抽沙能力不均,严重影响运行排沙效果。等阻力树杈型冲沙管道是近期提出的一种新型排沙方式,其各级管道采用树杈型布置,多口汇流的旋转流动可消除不同角度水流加速度影响,按每一个进口管至总出口的流动阻力相等为原则设计;在进口管顶部设置倒扣铁锅型防沙罩,防止进口管被落淤的泥沙所阻塞。本文在水槽中开展了树杈型冲沙管道试验,同时开展了相同条件下的进沙口顺序排列的对比试验,结果表明:当进沙口按传统廊道多口顺序排列布置时,位于远端的一半出口将被完全淤堵,难以达到预期的排沙效果;而树杈型冲沙管有效克服了传统廊道不同进沙口抽沙能力不均的缺陷,实现了对所覆盖区域的均匀排沙,正常情况下未发生淤堵;当高含沙水流集中流向某一进口时,会造成该进口淤堵,但由于不同进沙口独立运行,所淤堵进口基本不会对其他进口的正常运行造成影响。本文试验结果表明,等阻力树杈型冲沙管道的稳定排沙浓度可达400～700 kg/m3,远高于顺序排列方式的100 kg/m3;冲刷漏斗体积为多口顺序排列的1.5倍。

Experimental study on an equal-resistance and tree-like branching sediment flushing pipeline system

Reservoirs built on a heavy sediment laden river must confront severe challenges of sedimentation, and the reasonable and scientific measures to restore and maintain the reservoir capacity are of great significance to keep the comprehensive benefits of the reservoir. The sediment flushing tunnel has been considered one of which facilities with one-time construction and can be used in a sustainable way. However, the different inlet ports in a traditional flushing tunnel are often arranged in sequence,as a result,the suction capacity of different ports is uneven,which seriously affects the effect of sediment discharge. Equal resistance and tree branch type sediment flushing pipeline system is a new type of sediment remove measure proposed recently. In this method, the pipelines at different levels are arranged alike as tree branch, and the rotary flow of multiple confluences eliminates the influence of water flow acceleration at different angles. It is designed according to the principle that the flow resistance from each inlet pipe to the overall outlet is equal. Moreover, an up-side down iron pot type shield is installed on the top of the inlet pipe to prevent it from being blocked by the falling sediment. In this paper, a series tree branch sediment flushing pipeline system experiments was carried out in a water tank,as well as comparative tests based on the sequence arrangement inlets under the same conditions. The results show that when the multiple inlets was arranged in the sequence way, as them in a traditional flushing tunnel, half of the inlets located at the far end would be completely blocked, making it difficult to achieve the expected effect for sediment flushing. However, the tree-branch flushing pipeline system effectively overcomes the defect of uneven pumping capacity distribution of different inlet ports in the traditional tunnel, a state of uniform and stable sediment discharge in its covered area without blockage was achieved under normal circumstances. When the high concentration of sediment flow focuses to a certain inlet, which will be blockage gradually. Nevertheless, due to the independent operation of different inlets,the blockage of the inlet will have little effect the normal operation of other inlets. The test results show that the stable sediment concentration of the equal-resistance tree branch flushing pipeline system flow can reach up to 400~700kg/m³, which is much higher than 100kg/m³ in the sequential arrangement, and the volume of the scour funnel is 1.5 times that of the sequence of multiple ports.