Study On Siphon Water Supply Flow Of Loess Slope Protection Plants

Geological disasters occur frequently in the loess area,and landslide disasters are the most serious.Plant slope protection is widely used as a cost-effective slope protection technology.However,due to the drought and lack of rain in the loess area,the rainfall is concentrated and mostly heavy rain.The slope-protecting plants are prone to lack of water in the dry period after the rain,and the survival rate of the plants is reduced,which makes the slope protection effect poor.This paper learns from the successful application of siphon technology in the field of slope drainage and other fields,proposing a method of using water from the collecting pool to supply water to plants through siphoning based on the plant slope protection technology.It not only ensures the normal growth of plants,but also prevents the rainy season from scouring the loess slope.The method uses the advantages of siphon technology including utilizes free power,long distance transport and controllable flow rate.and it conveys the water to the slope-protecting plants by means of micro-release.It can form a drip irrigation effect and improves the survival rate of the slope-protecting plants.As a important parameter for the application of this method,siphon flow is of great significance for the design of siphon tube and pool.In this paper,the siphon flow of the 1-2mm siphon tube for this method is studied in depth.The relevant laws are explored through theoretical calculation and physical simulation test.The conclusions are as follows:(1)During the siphoning process,the pressure inside the siphon tube decreases as the lift rises,and a large number of bubbles are generated in the siphon tube.The siphon flow is divided into water flow and bubble flow at this time.The water flow is the key for this method.To solve the water flow,the bubble flow needs to be analyzed first.Becase the flow ofl-2mm siphon tube is little,the theoretical calculation formula of the bubble flow is derived based on the relevant physical and chemical laws.It indicates that it is positively correlated with temperature,head,oxygen and nitrogen dissolved amount,and negatively correlated with tube length and local atmospheric pressure.Compared with the results of the physical simulation test,it shows that the trend is consistent.(2)Based on the theory of hydraulics,the calculation formula of siphon flow is obtained.Compared with the siphon flow physical simulation test,the theoretical value is consistent with the experimental value,but the experimental value is too small.The analysis shows that this phenomenon is caused by the calculation error of the resistance coefficient along the path during low lift and is affected by the bubble resistance at high lift.Through fitting analysis,the empirical calculation formula of siphon flow of 1-2mm siphon tube is obtained,and the error analysis meets the accuracy requirement.In actual engineering applications,siphon flow can be obtained through experiments,and siphon flow can be calculated by empirical formula.The two methods provide a reliable basis for engineering application of siphon water supply method for loess slope slope protection.(3)The physical simulation tests show that when the lift is lower than 6m,the siphon flow does not change with the lift.When the lift exceeds 6m,the siphon flow is negatively correlated with the lift.The siphon flow is positively correlated with the pipe diameter and elevation difference,and the siphon flow is negatively correlated with the pipe length.The local lift loss has little effect on the siphon flow,accounting for less than 1%.The lift loss along the path has a greater impact on the siphon flow,accounting for more than 99%.Therefore,the siphon tube layout can ignore the influence of the winding of the tube.(4)Physical simulation tests show that the siphon flow of the 1-2mm siphon tube is in the range of 0.7L/h?4.0L/h.Using the empirical formula of loess infiltration wetted body,the water provided by a single siphon tube with a diameter of 1-2mm can infiltrate most of the roots of the slope-protecting plants for up to 4 days.In an actual engineering,multiple siphon tubes can be used to supply water to the plants.It can reach the effect faster.