Study Of Flow Distribution Characteristics In City Stormwater Sewer And Roadway Coupled Drainage System Using Hydradynamic Models

Rapid urbanization process increases the proportion of impervious underlying surface which leads to frequent flood and great economic loss.Designing urban roads as drainage channel under heavy rainfall events and building sewer and roadway coupled drainage system are important ways to solve urban waterlogging.However,there are still technical shortcomings for design and calculation methods,which limits the application of this technology.Aiming at this,research on flood capacity and influencing factors of coupled drainage system under different hydraulic boundary conditions is carried out.GIS information representation algorithm for regional flood capacity prediction is constructed and applied.Secondly,a road drainage plane distribution algorithm is constructed to predict flow distribution better under different road design parameters and then is coupled with SWMM.Finally,according to the proposed algorithm and coupling model,waterlogging points in study area are identified and coupled drainage system is designed and reformed.Results show that couple of correlation algorithm and model can overcome the problem of insufficient precision of SWMM hydraulic model to simulate coupled sewer and roadway drainage system to some extent,and provide flow constraint conditions and optimization direction for the analysis of waterlogging and design of coupled drainage system.The research results are as follows:(1)Study on the prediction model of maximum flood capacity of coupled sewer and roadway drainage system.1)Under free boundary condition,maximum flooding capacity of road has a positive linear correlation with road width,and increases first and then decreases with the increase of road slope.The maximum flood capacity of sewer has a positive linear correlation with sewer slope,depth and diameter.2)When sewer diameter is greater than 800 mm,coupled system flood capacity is affected by sewer design parameters more.The highest weight value among design parameters affecting flood capacity is sewer diameter,followed by buried depth and slope.When sewer diameter is less than 800 mm,coupled system flood capacity is affected by roadway design parameters more.The highest weight value among design parameters affecting flood capacity is roayway,followed by slope.3)When downstream water level reaches to the critical level of sewer network,the trend of system’s flood capacity changing with related design parameters is consistent with that of free outlet condition,but compared with free boundary condition,the flood capacity is greatly reduced with the reduction rate between 6.2%-82.7%.4)When downstream water level reaches to the highest level of roadway discharge,road maximum flood capacity is positively correlated with road width.Road maximum flood capacity varing with road slope is related to sewer diameter.Sewer maximum flood capacity is positively correlated with sewer slope.Sewer maximum flood capacity varing with sewer diameter is related to sewer slope.Compared with free boundary condition,flood capacity is greatly reduced with the reduction rate between-15%-87%.(2)Study on plane distribution model of road drainage intersection1)Based on continuity,energy conservation and momentum conservation equations,optimization method is used to solve the diversion flow of branch road under different road design parameters in MATLAB software.Results show that split ratio of branch road is negatively correlated with upstream flow rate,upstream froude number and slope of main road,and positively correlated with branch/main road width ratio.2)When main and branch road width equal to 7m,the split ratio of branch road is between 5.5%-27.8%;when main road width equals to 14 m and branch road width equals to 7m,the split ratio of branch road is between 5.4%-20.7%;when main and branch road width equal to 14 m,the split ratio of branch road is between 5.5%-29.7%.3)Compared with existing empirical solution,this proposed algorithm calculation error is smaller than the existing empirical solution error,and is more suitable for the intersection flow calculation of urban road scale.(3)Road drainage intersection plane distribution algorithm is coupled with SWMM hydraulic model.In this coupled model,outlet and weir flow settings are used to achieve flow diversion in road intersection.Results show that outlet setting at the intersection is more accurate to simulate water division.(4)Applying the coupling model to research area,the planning,designning and reconstruction of sewer and road drainage system in this area are carried out according to the above research results,which can also provide reference for the design of waterlogging prevention and flood control engineering in the future.