机压微灌管网系统布置与管径同步优化设计

微灌管网系统由轮灌管网(支毛管)和续灌管网(干管)组成,以往的研究没有将其作为一个系统,且不能实现布置与管径组合的同步优化,研究成果对坡度均匀的大型灌区机压微灌独立管网系统的优化也不适用。因此,提出了机压微灌管网系统优化的方法,并建立了优化设计数学模型,采取整数及实数编码的混合编码方法,通过遗传算法求解,同时实现轮灌管网及续灌管网的布置优化及管径组合优化,得出的管径为标准商用管径,无需调整。实例计算结果表明,该模型与算法在求解机压微灌管网系统优化设计问题上具有良好的优化性能和求解精度。与传统设计方案相比较,轮灌管网和续灌管网的优化设计方案单位面积年费用分别降低了14. 85%～35. 59%和4. 12%～12. 99%,节省投资效果明显。

Simultaneous Optimization of Layout and Pipe Diameter for Pumping Micro-irrigation Pipe Network System

The problem of selecting the best pattern of layout and pipe diameter of each pipe in the micro-irrigation pipe network system has long been given considerable attention by engineers and obtained numerous research results. Micro-irrigation pipe network system is composed of rotational irrigation network (manifold and lateral) and continuous irrigation network (main and submain pipe). Previous studies did not treat micro-irrigation pipe network system as an integral and can not realize the simultaneous optimization of layout and pipe diameter combination. In addition, research results can not be applied to the optimization of pumping micro irrigation pipe network system for large irrigation area. The optimization method of pumping micro-irrigation pipe network system was proposed. The mathematical models of rotational irrigation network and continuous irrigation network were established. The best control area, layout and pipe diameter of rotational and continuous irrigation network can be obtained simultaneously by solving the mathematical model with dual coding genetic algorithm. Commercial pipe diameters can be obtained through the optimization without adjustment. Examples showed that the algorithm was of good convergence and high precision on optimization problem of pumping micro irrigation pipe network system. Compared with the traditional design scheme, the annual total cost per unit irrigated area of optimized design scheme for rotational irrigation network was reduced by 14.85%~35.59%, and the annual total cost per unit irrigated area of optimized design scheme for continuous irrigation network was reduced by 4.12%~12.99%. The simultaneous optimization method of layout and pipe diameter can be applied to the optimal design of pumping micro irrigation pipe network system on uniformly sloping fields which with sufficient water source. The research result had important theoretical value and practical significance in the optimization of pumping micro-irrigation pipe network system for large irrigation area.