The Research Of Reconstruction Of The Old City Water Supply Network Based On Risk Assessment Technology

With the rebuilding and extending demand of the old urban water supply pipe network project,the way of the old urban water supply pipe network expansion in the transformation process in a certain experience is blindness,while the economy also caused some waste.It is of great significance to establish a perfect safety risk assessment system in the process of water supply network expansion,to establish scientific management scheme,reduce leakage,optimize water supply network layout and improve water supply safety.This paper mainly aims at establishing a safety risk assessment system for the old urban water supply network of J city.Based on the evaluation results,this paper puts forward a scientific and reasonable optimization plan to guide the expansion of the pipe network.The main situation of the water supply system in J city was investigated,and the total pipelines are 27 km.The pipe material mainly includes ball cast iron pipe,gray cast iron pipe,UPVC pipe,PE pipe and pipe diameter are mainly distributed in 200 ~700mm.19 secondary water supply systems were investigated,mainly including the secondary water supply networks,external networks,secondary water supply equipments.The results show that the water supply pipe network is in disrepair,the actual operation of the pipe network is not well.The external networks and internal networks of secondary water supply system have serious aging,the secondary water supply equipments are aging,the drainage pipes and the water supply pipes in the trench have leakage and other phenomenas.Indicating the existence of safety risk assessment in the old urban water supply network is neccessary.The establishment hydraulic and water quality risk assessment system of the water supply network of J city.Based on the important pipe section analysis module in InfoWorks WS software,the water supply pipe section is tested according to theactual water pressure change,the number of nodes,the number of nodes below the minimum pressure,the number of nodes above the maximum pressure,the lower threshold pressure change,the upper threshold pressure changes to determine the risk pipes,and the initial area of these pipe sections identified as the regions of the transformation;water quality assessment is to select seven secondary water quality monitoring points and seven municipal water quality monitoring points to establish monitoring system,results of the water quality monitoring points were compared,and the secondary water supply quality model of J city was established.The change of the secondary water supply quality(residual chlorine)was simulated.The results showed that the water quality of the users was polluted by the secondary water supply system,Combined with the results of the initial investigations to determine the secondary water supply system transformation areas.Study on the application of urban water supply pipe network expansion and secondary water supply renovation project in J city.Research on the old city water supply pipe network block technology,based on the results of hydraulic risk assessment,the water supply pipe network is partitioned by pressure partition method,and the actual situation of each area is analyzed to analyze the problems caused by the high pressure or low pressure of the pipeline in the area.Research on the secondary water supply system optimization and transformation technology,and the secondary water supply external network,the internal network transformation and the dismantling terrain,district secondary water supply facilities,the integration of high-level district secondary water supply facilities,additional secondary water supply facilities to solve the problem of insufficient water pressure,installation of online monitoring system,water meter home transformation are carried out in the 12 secondary water supply systems reconstruction areas identified by the water quality risk assessment.After the overall transformation of the city's water supply systemrunning in good condition,in the protection of water quality under the premise of achieving a balanced water pressure,reduce pipe network loss rate,saving energy consumption purposes.