Abstract:

In order to improve the ability of accident prevention and risk control of urban drainage networks, first of all, based on the indicators from the four aspects of "human-material-management-environment", 19 assessment indicators were obtained to construct the risk assessment index system of urban drainage pipe networks, and a risk evaluation index system for urban drainage networks was established accordingly. Subsequently, a model of urban drainage networks was constructed by integrating fuzzy theory and BN. Triangular fuzzy numbers were introduced to quantify the scores of experts. Weights were assigned according to differences in professional titles and working years, and α-weighted valuation method was adopted to transform fuzzy evaluations into clear probabilities. Thus, a risk evaluation model for urban drainage networks was obtained, and forward and reverse reasoning of BN was conducted to calculate the posterior probabilities of key nodes. Finally, taking the drainage network of a certain urban area as an example, the risk level of the drainage network in a specific area of the city was evaluated, and investigations were conducted for verification. The results indicate that the model effectively handles uncertainties and subjectivity in the risk assessment process, achieves probabilistic characterization of drainage network risks, and improves the accuracy of evaluation outcomes. External pipe protection is identified as the most critical factor affecting drainage network safety, followed by anti-corrosion measures and joint methods. The overall safety performance of the urban drainage network is found to be satisfactory, with risks remaining within controllable limits. Comparative analysis with historical monitoring data and fault records confirms the practicality and reliability of the model.

Key words: Bayesian network (BN), drainage network, risk assessment, posterior probability, risk level