Optimization Design Of Anti-seepage Channel In North China Plain Area

In view of the shortage of agricultural irrigation water resources in China,this paper aims to improve the utilization efficiency of irrigation water by improving the anti-seepage channels in the north China plain area.In the semi-arid area of the north China plain,there is a shortage of water resources,and the over-production of groundwater is very serious.In order to conserve water resources,there is a great deal of pressure on groundwater in north China,and the water consumption of agricultural irrigation is greatly restricted.Therefore,vigorously developing water saving irrigation,is the realization of the sustainable development of agricultural water priority.In recent years,water-saving irrigation methods in north China had been dominated by channel impermeability.The anti-seepage channel could effectively reduce the loss of water,and the construction is convenient and the cost is low,which were an important engineering measure for the development of water-saving irrigation.The anti-seepage channel is based on the full assurance of the water supply,and the optimal design of the water section and the slope of the water,through reasonable optimization design,to effectively reduce the investment in engineering,reduce the loss,reduce the cost of running the operation,and enhance the efficiency of irrigation water efficiency.The forms of antiseepage channels are various,and the common cross-section forms are: moment form section,ladder form section,U-shaped section.In the design of cross-section of anti-seepage channel,first of all,to meet the requirements of irrigation flow,the cross-section should have enough water capacity.Secondly,the flow velocity in the anti-seepage channel should be appropriate,and the design flow rate should be less than the allowable flow rate,which is greater than the allowable non-silting velocity.Thirdly,there should be a stable channel bed,so that the flow of water will not sway to the left and right side of the channel bed and the slope,and the sediment balance.Finally,the problem of comprehensive utilization should be considered to minimize leakage loss and high utilization coefficient.Many scholars had studied it in detail,but the longitudinal slope design of anti-seepage channels were seldom noticed.Based on the previous studies on cross-sectional studies,this study increases the joint optimization of the longitudinal sections of different longitudinal slopes,so as to reduce the size of anti-seepage channels,improve the efficiency of water transmission,reduce the loss of water head,and improve the efficiency of irrigation and water utilization and reduce the purpose of investment in engineering.In this paper,the joint optimization of the cross section of the anti-seepage channel is carried out,which provides a better theoretical basis for the engineering design of the antiseepage channel in practice.In this paper,the mathematical model of channel cross-sectional optimization is established by using the SQP algorithm(sequential quadratic programming)of MATLAB.Based on the constant and uniform flow of the open channel,the optimal analysis of the hydraulic optimal section is carried out for five different types of cross sections with the manning formula,and the best results of the optimized analysis are finally applied.At the same time,the optimization method of planning and solving by MATLAB is mastered.Through the analysis and comparison of the optimization model,the main conclusions are summarized as follows:(1)Rectangular cross section under different longitudinal slope conditions,the width and depth ratio of the open channel of the optimal section of hydraulic section is 2;(2)The triangular cross section under the condition of different longitudinal slope,channels hypotenuse horizontal Angle is 45 °,shows two hypotenuse triangle channel Angle is 90°,namely when the triangular cross-section channel cross-sectional hypotenuse for right Angle for optimal hydraulic section;(3)Arc at the bottom of U-shaped cross section under the condition of different longitudinal slope,tangent point circle connect with horizontal Angle is 90°,the circular cross-section channel at the end of the bottom of the optimal hydraulic section are half arc;(4)The radius of the hydraulic optimal section of the U-shaped cross section of the arc is proportional to the proportion of the water depth;(5)For the parabolic cross section channel optimization analysis and formula derivation,it is concluded that under the condition of different grade for optimal hydraulic section parabola and depth of the constant is approximately equal to 0.947,the product of knowable parabolic cross section channel optimal hydraulic section are satisfied with ch?947.0;(6)Regardless of the shape of the cross-section,the larger the value of the longitudinal slope is,the greater the value of the wet week is in the case of the cross-section of the same shape;(7)In this paper,the analysis of five kinds of cross section in the form of a channel,in the range of allowable choice under the condition of minimum longitudinal grade value of circular arc at the bottom of the u-shaped cross section channel water ability best,at this time for the channel capacity of the optimal combination.