| Stormwater inlets consisting of grates inlet and continuous transverse grates inlet serve as the linkage between the surface drainage system and the underground sewer system,and their interception efficiency determines the water depth on the road and the drainage efficiency of the underground pipe network.Therefore,the research on the key factors affecting the interception flow and interception efficiency is of great significance to optimize the design of urban drainage systems.A full-scale physical model of simulating a 12 m long and 3 m wide road was constructed for 204 hydraulic tests for five types grates inlets and 320 hydraulic tests eight continuous transverse grates inlets for eight types continuous transverse grates inlets,and the influences of grate types,approaching flow rates,road longitudinal slopes,road transverse slopes and road paving materials on interception flow rate and interception efficiency of inlets were investigated.The results of grates inlet tests show that the influence of grate type on interception flow and interception efficiency is not significant within the scope of the experimental study.Increasing the approaching flow rate,the interception flow rate increases and the interception efficiency decreases;increasing the cross slope,the interception flow rate and efficiency increase significantly.Compared to the inlet grates only with longitudinal openings or transverse openings,the grates having both of longitudinal and transverse openings can improve the utilization rate of openings,thus improving the interception efficiency.Based on the Manning Equation and the orifice outflow formula,a set of empirical equations were proposed to estimate the efficiency of the five tested grate inlets and were compared with other theoretical formulas.Good agreements were obtained between the predicted and measured results with relative difference of less than 7%.A new type of grate with high interception efficiency was created and the efficiency improvement was verified through tests.The results of continuous transverse grates inlet tests show that the hydraulic efficiency of different continuous transverse grates may not have a consistent relationship with the Froude number.It is found that the grate length dominates the value of the efficiency,while the effective width ratio determines the pattern.When the opening shape changes from rectangular to circular,the pattern of grate’s hydraulic performance changes significantly.Compared to grates with rectangular openings symmetrically arranged,when the opening area and rate are the same,the grates with circular openings staggerly arranged were found to perform better for capturing runoff.Based on the Manning Equation and the orifice outflow formula,a set of empirical equations were proposed to estimate the efficiency of the eight tested continuous transverse grates.Good agreements were obtained between the predicted and measured results with relative difference of less than 15%. |
PDF Full Text Request