Practice And Exploration Of Separation Of Rainwater And Sewage In Drainage System Reform In Old Town Of Yantai

As an important central city in Shandong Peninsula,international coastal tourist resort city,international port city,national innovation city and so on,Yantai is taking on more and more important urban functions in the development of the country.However,in recent years,with the continuous expansion of the urban scale of Yantai and the rapid growth of population,the drainage system of Yantai has gradually exposed many problems.For example,urban waterlogging?sewage overflow?river pollution and other problems.The cause of the problem:First,the drainage facilities are not perfect,the drainage design standard is low,and a small number of areas do not have rain water,sewage discharge facilities.Rainwater surface runoff,sewage without treatment directly discharged to the nearest river,or infiltration underground;Second,the drainage system of Yantai is a combined drainage system of rain and sewage,and the rainwater and sewer pipes are lapped.The sewage pipe is connected to the rainwater pipe,which is discharged directly to the nearby river channel and sea,resulting in water environment pollution.The rainwater pipe is connected to the sewer pipe and discharged to the sewage treatment plant,which not only reduces the treatment efficiency of the sewage treatment plant,but also increases the operating cost of the treatment plant;Third,the municipal drainage pipe network is not perfect,the new residential area and commercial district within the urban area,lack of supporting municipal supervisor network,resulting in rain water,sewage nowhere to discharge.The existing drainage infrastructure is far behind,so it is difficult to meet the construction and development plan of Yantai Mayor's period.Based on the practice background of the rain pollution diversion project in the old city of Yantai,combined with the present situation of early drainage in Yantai,this paper puts forward the necessity of the rain pollution diversion transformation in Yantai through the analysis of literature analysis,field investigation and other interdisciplinary research methods.Its findings are as follows:1.Through the literature analysis method to the foreign and domestic typical city drainage course research,summarizes the cities inside and outside the country in the process of drainage development experienced changes and advanced experience.And through drawing lessons from domestic and foreign advanced drainage experience,for the future guidance of Yantai drainage facilities reconstruction to do a good job.2.Combining with the research and comparative analysis of the drainage system(combined flow system,combined flow closure system,diversion system)of Yantai city before the transformation,the paper summarizes the drainage system which is most suitable for the development of Yantai-the complete shunt drainage system.The complete shunt drainage system is the correct choice of the future development plan of Yantai city and the construction of basic municipal drainage facilities,which lays a good theoretical foundation for the sustainable development of Yantai drainage system.3.According to the drainage situation and road planning situation of Yantai,the old urban area of Yantai is divided into nine districts.According to the different drainage problems in each area,the corresponding design and transformation scheme is put forward.The latest design parameters and design formulas are adopted in the design of rain and sewage pipelines,and the specifications and materials of rain and sewage structures are uniformly planned.From the index ratio of all kinds of pipes,the reinforced concrete pipe and FRP sand-clamped pipe are selected as the rain and sewage pipe in Yantai.4.In the transformation of rain pollution diversion,the key and difficult problems in the construction site are solved,such as lowering the groundwater level by large-caliber precipitation method,taking concrete encapsulation and protection measures for the original underground facilities,and the migration and access problems of the old pipelines.5.Based on the application and research of non-excavation technology(closed pipe jacking,micro-tunnel method,micro-shield method,horizontal directional drill,rammer pipe method)and the traffic and environment conditions of Yantai,this paper explores the non-excavation technology-closed top pipe method suitable for the reconstruction project of rain pollution diversion in Yantai.Because there is no complete standard and relevant standard in our country at present,this paper analyzes and studies the reconstruction project of rain pollution diversion in the old urban area of Yantai,and also has some reference significance for the reconstruction of rain pollution diversion and drainage facilities in other old urban areas in China.