灌溉沉沙池泥沙设计标准研究

Study on design standard of de-silting basin for irrigation

灌溉沉沙池的设计标准是沉沙池设计的重要依据,包括入池和出池泥沙设计标准,内涵含沙量和级配两个指标。确定入池设计标准时,宜以引水期分析统计得到的具有代表性的入池泥沙特征值作为设计值。自流灌溉沉沙池出池含沙量的控制,应以干、支渠不产生淤积为标准,平原区沉沙池取值可低些,可以2～7kg/m3作参考;山区沉沙池取值可高些,可以12～50kg/m3作参考。泵站沉沙池出池含沙量应综合考虑泵站扬程、泥沙粒径对水泵磨损的影响,并结合下游干、支渠挟沙力要求,通过论证后确定。灌溉沉沙池出池泥沙粒径宜控制在小于0.05mm以下,0.05mm以上粒径的泥沙沉降率可取80%～85%。

The design standard of the de-silting basin for irrigation is an important basis for the design of the de-silting basin, which includes the sediment design standards for both the incoming flow and outgoing flow with the indexes of both the sediment content and gradation. It is better to determine the design standard for the incoming flow by taking the characteristic value of the representative incoming sediment obtained from the statistic analysis during the water delivery period. For the gravity irrigation, not causing siltations in trunk and branch canals must be taking as the design standard for control of the sediment content of the outgoing flow. For the de-silting basin constructed in plain areas, lower sediment content value can be taken, i.e. 2 ～ 7 kg/m^3 can be taken as the reference, while for those basins in mountainous areas, the higher values can be taken, i.e. 12 ～50 kg/m^3 can be taken as the reference. The sediment content of the outgoing flow from the de-silting basin of pumping station must be determined after the related certification under the comprehensive consideration on the lift head of the station, the wearing effect on the pump from the particle size of the sediment in combination with the requirement of sediment carrying capacities of the trunk and branch canals downstream. For the de-silting basin for irrigation, the sediment particle size of the outgoing flow is better to be controlled under 0. 05 mm and the sedimentation rate of 80% ～85% can be taken for the sediment with the particle size over 0. 05 mm.