Analysis And Assessment Of Urban Water Supply Pipeline Integrity

Water supply pipelines play an important role in the urban water distribution system(WDS), they are the link between water plants and users. All the water supply pipelines used were laid year by year with the development of the city. And the old pipelines are often prone to have breakage, which not only bring economic loss to the water plants and enterprises, but also inconvenience to city life. Some water supply pipeline projects, such as pipeline maintenance and transformation, can effectively reduce water supply pipeline breakage, but there is still not established decision support system for them. In the study, the theory of pipeline integrity(PI) was applied to urban WDS. And the water supply pipeline integrity analysis and assessment are prerequisite to the optimized implementation of water supply pipeline projects, and they are the decision support for consideration of economic and efficiency.Around the theory of pipeline integrity, research constructed the water supply pipeline integrity analysis and assessment model, which was based on three models. They were water supply pipeline breakage probability analysis model, water supply pipeline failure consequences assessment model and water supply pipeline risk assessment model, they each respective different issues, predicting the probability of pipeline breakage, impact assessment after the valves were closed when there was breakage, and pipeline risk rate. Exactly the water supply pipeline breakage probability analysis model was established with fuzzy analytic hierarchy process(FAHP) and probability statistical distribution. The water supply pipeline failure consequences assessment model is a comprehensive evaluation model, which took the node demands decrease of affected pipelines, the node demands decrease and the pressure reduction of non-affected pipelines as three estimate indexes. And two assessment models were established, which were subjective weight defining method one hierarchical assessment model and objective weight defining method two hierarchical assessment modle, and the latter is more accurate after comparing them. The water supply pipeline failure consequences evaluation model based on water supply pipeline failure hydraulic model which first redistributed node demands, specially treated valves and pipelines in the EPANET software, and automatically adjusted the node demands under node pressure, and was calculated by genetic algorithm(GA). The water supply pipeline risk assessment model was a product model formed by water supply pipeline breakage probability analysis model and water supply pipeline failure consequences assessment model. And the pipeline integrity was synthetically reflected throw the results of the water supply pipeline integrity analysis and assessment model.Through the simulation experiments in a small water distribution system, it showed that all the models worked well. According to the results of the models, the research proposed measures to improve the pipeline integrity from reducing the probability of water supply pipeline breakage, reducing water supply pipeline risk and so on. What's more, the water supply pipeline integrity analysis and assessment model was introduced to the water supply network planning in one oilfield region in East China. According to the model's simulation results, some planning proposals had been proposed and nearly all of them were adopted. The model worked very well.