| Based on the existing research on muddy water film hole irrigation technology,this paper refers to relevant research at home and abroad,combined with the National Natural Science Foundation of China,aiming at the current situation of irrigation in the irrigation area of northern China and the characteristics of muddy water and mud sand in the Yellow River Basin,the indoor test and theoretical analysis are combined.The research method reveals the formation characteristics of the dense layer of free infiltration of muddy water film hole irrigation and its influence on the infiltration law of film hole irrigation.The main research results are as follows:(1)The formation characteristics of the silt layer under film hole irrigation were studied.The soil bulk density,sediment concentration of muddy water,film hole diameter and muddy water gradation all had significant effects on its thickness change.The thickness of the silt layer affected by different factors increases with the increase of infiltration time,and the relationship between the two is a power function.The calculation model of silt layer thickness under the influence of different factors is established.(2)The effects of soil bulk density,sediment concentration of muddy water,film hole diameter and muddy water level on the particle composition of free infiltration dense layer of muddy water film hole irrigation were revealed.Compared with the particle composition of muddy cement sand,the content of fine particles in the sediment layer at the end of infiltration is less,and the content of coarse particles is more.With the increase of sediment concentration,membrane pore diameter and physical clay content,the phenomenon of sediment retention is more obvious,and with the increase of soil bulk density,the retention phenomenon is weakened.The retention layer range of free infiltration of muddy water film hole irrigation under various factors was obtained.(3)Through the study of infiltration characteristics of film hole irrigation,it shows that the Kostiakov model can well describe the relationship between cumulative infiltration per unit area and time,and the wetting front migration distance increases with the increase of water supply time.An empirical model of cumulative infiltration per unit area and wetting front migration distance under different factors was established.The moisture content of the wetted body in the horizontal and vertical directions decreased with the increase of the distance from the center of the membrane hole,and finally tended to the initial moisture content of the soil.At the same position of the wetting body,the larger the diameter of the film hole,the greater the water content,while the influence of soil bulk density,film hole diameter and physical clay content on the water content law is opposite.At the end of infiltration,the soil moisture content of each test treatment near the film hole water chamber was close to the saturated soil moisture content.(4)The effects of soil bulk density,sediment concentration of muddy water,membrane pore diameter and muddy water gradation on the thickness of silt layer,cumulative infiltration per unit area and vertical migration distance of wetting front were comprehensively analyzed.The influence degree of each factor on the thickness of silt layer was soil bulk density,sediment concentration of muddy water,physical clay content and membrane pore diameter.The influence degree of cumulative infiltration per unit area from large to small is film hole diameter,soil bulk density,muddy water sediment content,physical clay content.The degree of influence on the vertical migration distance of the wetting front from large to small is membrane pore diameter,muddy water sediment content,soil bulk density,and physical clay content.The empirical models between the thickness of the falling silt layer,the cumulative infiltration per unit area,the vertical migration distance of the wetting front and the various influencing factors were established respectively. |
PDF Full Text Request