Based On Numerical Simulation Of Canal Seepage Under Pressure Infiltration And Prediction Method Of Infiltration Model Parameters

Canal seepage is an important basis for evaluating the effect of seepage control measures and planning of irrigation areas.The amount of channel leakage is greatly affected by many factors,and the current calculation methods of channel leakage have their own advantages and disadvantages,and the applicable conditions are different,and it is difficult to establish the internal relationship between the influencing factors and the calculation methods.Channel water infiltration is the channel leakage loss,so the amount of channel leakage can be expressed by soil infiltration model The suitable conditions of different soil infiltration models are not the same,and the model parameters are affected by different factors.The pressurized infiltration conditions formed in the case of larger channel water depth are completely different from surface irrigation infiltration in terms of infiltration driving force,so the channel water movement is closely related to channel hydraulic factors dominated by channel water depth in addition to basic physical properties of soil and other factors.There fore,the research on the influencing factors of channel leakage is equivalent to the research on the influencing factors of the parameters of the infiltration model applicable to the channel,which has always been one of the important topics in the field of water conservancy engineering.Therefore,this paper takes the soil water movement equation as the theoretical basis to explore the variation law of soil water infiltration characteristics under the condition of canal pressure infiltration.On the basis of field tests,the relationship between the parameters of soil water infiltration model and the hydraulic factors of channels,mainly including water depth,is studied by means of numerical simulation.The prediction method of infiltration model parameters is proposed,and the infiltration model expressed by hydraulic factors of channels is obtained.The main research results are as follows:(1)The water depth of different channels has great influence on soil infiltration characteristics.The cumulative infiltration amount,infiltration rate and leakage intensity under different water depth increased with the increase of water depth.The cumulative infiltration amount,the stable infiltration rate and the stable seepage intensity all increase exponentially with the increase of channel water depth.In the test,the optimal water depth with relatively large water depth and moderate infiltration characteristics was selected as 70cm.(2)According to statistical analysis,the Kostiakov two-parameter cumulative infiltration volume model has a good effect on water movement in the expression channel,The water depth of different channels has significant influence on the parameters of the infiltration model.The infiltration index showed a steady downward trend.(3)The hydrus-2d model is applied to the numerical simulation of water movement in channels,and the applicability of the model in this experiment is verified.On this basis,the process of water infiltration in different channels under different hydraulic factors is extended and simulated.The influence of channel bottom width and slope coefficient on the cumulative infiltration is significant.The interaction of water depth and bottom width has a significant effect on the cumulative infiltration.(4)The bottom width of the channel is positively correlated with the infiltration parameters,the slope coefficient is negatively correlated with the infiltration coefficient,and the infiltration index can be regarded as a constant value.Using the transfer function,the prediction model of channel hydraulic factors at different water depth stages on infiltration model parameters is established.The cumulative infiltration amount calculated by the infiltration model expressed by the hydraulic factors of the channel,namely the leakage amount under specific channel working conditions,is relatively accurate,and the relative error is controlled at about 10%.The research results of this paper can provide theoretical reference and guidance for the rational design of channels,the calculation of channel leakage under specific channel conditions,and the comparison of leakage losses of different channels.