Siphon Drainage Capacity Theoretical Calculation For Debris Flood

China is a multi-mountain country,vulnerable to various natural disasters.Debris flow,as a kind of frequent occurrence natural disasters,has high catastrophability,causing huge disasters and properties loss every year.So many researches focus on the topics about debris flow control prevention.However,it had been proved that hydrodynamic factors were the basic conditions leading to the occurrence of debris flow.At present,all dewatering and diversion of debris flow preventions to eliminate hydrodynamics are using gravity drainage.Such preventions systems not only have shortcomings like high engineering and construction cost,long construction period and low drainage efficiency,but also easy to be clogged by the sedimentation.Leading to failure of structure.Using siphon to separate water can avoid sedimentation by its self-starting and dredging capacity,what's more,it can significantly improve the efficiency of drainage and durability.Nevertheless,there is no current formation for siphon water separation pipe design.In this paper,t the hydraulics analysis and the derivation of the formula,obtained the formula to calculate the siphon drainage capacity,In this paper,the research based on the hydraulics analysis and the derivation of the formula,also considered the influencing factors as much as possible.Established the basic model.The diameter of siphon drainage pipe is given by d,the siphon length is 1,the head height is h,the slope angle is ?,and the curvature of the head Radius is ?.With the factors,the paper derived a formula for siphon drainage capacity calculation.The calculation of siphon drainage capacity was carried out according to the standard material of PE80 pipe,and get the diagram of basic calculation value a.For complexity slope type in the actual project,siphon drainage capacity cannot be simply regarded as straight line.So divided siphon pipe into multiple arcs or polyline forms,and summed up a formula for non-linear arrangement of siphon drainage capacity calculation.According to the different arrangement number of segments,the arc center angle and the turning angle of the folding line are discussed,10 sections and 4 sections,arc angle of 180° and 90°,turning angle of 90° and 45° are compared respectively.Through the straight line arrangement and polyline arrangement siphon drainage capacity formula,it can provide guidance for practical engineering design,siphon pipe diameter size and arrangement quantity choice.Through the theoretical calculation,the difference between the drainage capacity of the siphon and gravity drainage is compared,and the efficiency of the siphon drainage is verified.In the comparison calculation,the drainage of gravity flow is considered to be close to the full pipe flow,and the gravity drainage pipe is arranged according to the straight line.Using the result compared with the siphon drainage capacity of basic model arrangement,the 10 sections of 180°arc arrangement and 10 sections of 90°polyline arrangement.The drainage capacity of gravity drainage and siphon drainage is taken as a quantitative comparison basis,and the results are analyzed and summarized.The comparison between siphon drainage and gravity drainage provides theoretical basis.