| In recent years,the construction of sponge city is vigorously promoted in China.The development intensity of southern cities is high.Among the underlying surfaces of urban built-up areas,urban roads account for a large proportion.Therefore,the sponge function of urban roads is of great significance to cities.Although domestic standards and regulations related to the function of urban road sponges have been issued in China,they are not particularly targeted to cities with high development intensity in the south.It is necessary to study and expand the functions of urban road sponges on the basis of existing urban roads,green belts and rainwater network specifications potentials and methods,and research on key technologies.The main research contents of this dissertation are as follows:The potential assessment and problem analysis of the current urban road sponge function are carried out,and the countermeasures for expanding the urban road sponge function are proposed.The optimization study on the cross section of urban roads found that the potential of the space sponge below the urban road green space,non-motorized vehicle lanes and pedestrian road surface is large.Considering the application effect and cost of permeable pavement,its limited sponge function makes it difficult to meet the requirements of rainwater infiltration and retention.Therefore,effective cross slope and vertical slope are recommended for road drainage.In order to give full play to the sponge function of the sunken greenbelt,it is urgent to optimize the soil layer thickness and longitudinal slope of the sunken greenbelt,and select the suitable greening plants for planting in the road sunken greenbelt.In order to meet the needs of "infiltration" and "drainage" in sponge city,the municipal storm water pipe can be punched and transformed to a permeable form.With Shenzhen as the background,technical research is conducted on sunken green belts and permeable municipal rainwater pipes.The sunken green belt adopts local original soil.Under heavy rain conditions,when the thickness of the soil layer is about 60 cm,the runoff through soil infiltration and temporary retention in the soil voids accounts for about 60% of the total runoff.When the soil seeps into the water,the removal rate of SS is above 90%.The removal rate of COD and TP is greater than 30%.When the slope of the sunken green belt is 1-3%,with the increase of the slope of the green belt,the upstream surface water storage and pollutant reduction are reduced.Spider orchid,lentinus edodes,canna and iris are suitable to be included in the plant selection system of shenzhen sunken green belt.The permeable amount of permeable municipal rainwater pipe is related to the nature of surrounding soil and the opening rate of the seepage pipe.Based on the pilot test and the SWMM model,the impact of road sponge measures on the quality and quantity of rainwater runoff and the impact of regional sponge measures on the carrying capacity of rainwater pipes are analyzed.The pilot experiment and are used to study the impact of subsidence green belts and seepage pipes on the quality and quantity of rainwater runoff.Under heavy rain conditions,the peak runoff reduction rate of the pipeline is close to 40%,and the SS removal rate reaches 60-80%.After subsidence green belts and seepage pipes are used,the annual total runoff control rate of urban roads can reach 73.2%.Using the SWMM model,the impact of regional sponge measures on the carrying capacity of rainwater pipelines was investigated.The results show that,under the same pipe diameter,regionalized low impact development(LID)measures can effectively reduce rainwater runoff and can reproduce the design of municipal pipelines.The period is increased from 1 year to 10 years.The combination of regionalized LID and municipal road permeable rainwater pipes can increase the rainwater pipeline design recurrence period from 1 year to 15 years.In one event,it significantly improves the flood control safety of rainwater pipes. |
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