Research On Design Of Urban Underpass Drainage System

Social and economic development in China has been at the forefront of the world since the reform and opening up,which is vigorously building roads and railways.However,as the available area of the city becomes smaller and smaller,the full use of urban space becomes more and more important.Many cities are accelerating the construction of underpass roads because that the low cost of the underpass,the ability to make full use of the space on the road and the impact of noise.The underpass roads account for up to three-quarters of the built overpasses,but with the massive construction of the underpass roads,the problem of easy water accumulation under the roads is becoming more and more prominent.Because the elevation of the underpass road is lower than that of the ordinary road by2 m or 8m,the rainwater in the rainy day flows under the drainage of the vertical slope of the road,and quickly flows into the lowest point of the road to form stagnant water.Long-term water accumulation seriously damages the pavement structure and shortens the service life of the road,which makes the vehicle unable to move forward.In severe cases,it will lead to traffic accidents,and the life safety of the driver's property will be threatened.This also checks and balances the development of the underpass road to a certain extent,so the problem of water accumulation in the city under the road needs to be solved urgently.This article will describe the causes and phenomena of under-water accumulation,focusing on the analysis of the problems in the design and drainage process of the entire drainage system under the road,in order to find a solution to the problem of water accumulation.First of all,the method of calculating the amount of rainwater by querying the domestic and foreign data comparison reasoning formula method,the mathematical model method,the void volume utilization method,and the capacity balance method of Professor Deng Peide of Tongji University.Then,the methods of dividing the rainstorm return period,the ground runoff coefficient and the catchment area at home and abroad are discussed.Finally,combined with various examples,the most suitable calculation method and calculation parameters of rainwater quantity are selected.This can save engineering investment costs while increasing the design standard for rainwater.Exploring and solving the causes and current situation of underlying road water accumulation requires not only research on rainwater volume design standards,but also in-depth research on its surface rainwater harvesting system.In addition,the scope of the gully and its scope of application should also be elaborated.Through the analysis of the drainage capacity of the flat,vertical and combined gullies,it is concluded that the flushing capacity of the flat gully is larger than that of the vertical raft,and the combined faucet is flat and vertical.In combination,although the amount of water discharged is also large and the flat raft can continue to collect water in the case where the sluice gully is blocked,the flat type can be widely used because of its complicated structure and high cost.The type of gully selected cannot solve the problem of stagnant water.Sometimes the road water is not because the rainfall exceeds the design standard of the drainage system,but because the spacing and quantity of the gully are not reasonable,the road garbage blocks the gully and the late management is poor.Now,some designers are usually more casual about the layout of the gully.Generally,a value is selected between 25 and 40 m.The drainage capacity of the gully is not studied.Therefore,the author believes that the cause of poor drainage of rainwater should be found.The spacing of the gully should be calculated by a reasonable calculation formula.The gully should be added at a specific location,and the method of setting the gully should be clearly defined in the curved section.The setting of the gully of the concave point and so on.The rainwater pumping station is the design core of the drainage system that runs through the road.This paper compares the advantages and disadvantages of different pump types,selects the water pump that fits the actual project,and selects the location of the rainwater pumping station and the pumping station.There is often a risk of water accumulation under the road,and the pumping station is at the lowest point of the road,which is easily flooded by rain.Therefore,when selecting a rainwater pumping station,a submersible pump is generally used,which is low cost,high degree of automation and reduces the manpower and material resources required in the later stage.During heavy rain,the pumping capacity of the rain pump station is insufficient.It is necessary to set up a rainwater storage tank at this time to reduce the peak flow.Therefore,it is necessary to analyze the type and characteristics of the rainwaterstorage tank,and select the appropriate calculation formula to design the volume of the rainwater storage tank.This analyzes the best urban underpass drainage system,thereby reducing the pressure of the lower tunnel drainage,making the drainage smoother and the possibility of water accumulation to a minimum.