改进暗管排水结构型式对排水性能的影响

提出一种占用耕地少、排水流量较常规暗排大且环境友好的改进暗排。基于室内土柱试验,分析改进暗排在地表积水、土体饱和条件下的排水除涝性能及其机理,提出地表积水土体饱和入渗条件下改进暗排排水流量的理论计算公式。结果表明,改进暗排可以有效提高暗管排水能力,试验条件下,反滤体宽度为2~6 cm的改进暗排在自由出流条件下的排水流量为常规暗排排水流量的2~3倍;积水层深度相同时,改进暗排排水性能随反滤体宽度的增加而增大,但增幅逐渐减小;土体介质和反滤体的渗透系数差别越大,改进暗排的排水作用越明显。理论方法计算结果与试验结果相吻合,证明提出的理论计算公式是合理可行的。

Effect of Structure-type on Improved Subsurface Drainage Performance

In China, there are large challenges for agricultural drainage system because of frequent flood and shortage of cultivated land, and new requirements are put forward to agricultural drainage system. Improved subsurface drainage was proposed which had characteristics of less cultivated land occupied, more environment friendly and larger drainage discharges than those of conventional subsurface drainage. Based on soil column experiment, the performance and mechanism of the improved subsurface drainage were analyzed under conditions of soil saturation and stable ponding surface water, which considered different soil textures, outflow conditions and ponding depths. Furthermore, a theoretical formula of improved subsurface drainage discharge was given. The results indicated that the drainage capability of the improved subsurface drainage was increased significantly. The drainage discharge equaled to 2~3 times of that of conventional subsurface drainage when filter width was varied from 2cm to 6cm under the experimental conditions. Drainage capability was increased with the increase of filter width, but the increased value was decreased gradually. In addition, the performance of improved subsurface drainage was going to be more obvious with the increase of gap between hydraulic conductivities of soil and filter. Compared the theoretical values with experimental ones, it was shown that the proposed theoretical formula was reasonable and feasible. The research results can provide technological support for the application of improved subsurface drainage. Meanwhile, the research will be beneficial to enrich theory and technology of agriculture drainage, which has important practical significance to ensure food safety and promote sustainable development of irrigated area.