农田暗管排水能力分析与提升方法探讨

在地下水位较高、地表易于形成积水的地区,探索经济可行的农田暗管排水措施,对于降低作物涝渍胁迫、提高作物产量具有重要意义。本文基于暗管排水流量理论公式分析了暗管排水能力影响因素及增强暗管排水能力的途径,提出在暗管出口处安装虹吸管,利用虹吸原理使其下端出流口降低到一定深度的虹吸增流方法。理论和试验表明,该方法可以大大提升浅埋暗管排水能力,且不增加暗管排水成本。浅暗管通过虹吸管出口降低到中埋和深埋时,即作用水头增加1.33倍和1.67倍时,排水流量增大33.3%和66.7%;由于浅埋管具有较小的渗流阻抗系数,其排水流量比相同出口的中埋管和深埋管大16%和27%。随积水层深度的减小,有虹吸的浅暗管排水流量虽然减小,但增流效果百分比在增大。该研究成果可为涝渍灾害易发地区建设高效除涝降渍减灾工程提供新途径。

Study on the capacity of subsurface pipe drainage in farmland and improvement methods

In the area where the water table is high and the surface is prone to water ponding, it is of great significance to explore the economic and feasible subsurface pipe drainage measures to reduce crop waterlogging stress and improve crop yield. Based on the theoretical formula of subsurface pipe drainage flow, this paper analyzes the influencing factors of subsurface pipe drainage capacity and the ways to increase the capacity of subsurface pipe drainage, and puts forward a siphon flow increasing method by using the siphon principle to install a siphon at the outlet of pipe, so as to reduce the lower outlet to a certain depth. The theory and experiments show that this method can greatly improve the drainage capacity of shallow buried pipe without increasing the cost of drain pipe. When the shallow buried pipe is increased to medium and deep buried through siphon, that is, the water head of shallow buried pipe increases by 1.33 times and 1.67 times, the drainage flow increases by 33.3% and 66.7%, and the drainage flow of shallow buried pipe is 16% and 27% larger than that of middle and deep buried pipe under the same drainage condition because of its small seepage impedance coefficient. With the decrease of ponding water layer, the drainage flow of shallow buried pipe with siphon decreases, but the percentage of flow increasing effect increases. The research results can provide technical support for the construction of high-efficiency waterlogging control and disaster reduction projects in the areas prone to waterlogging disaster.