Abstract: Piping was one of the main risks of dike engineering in China, thus it was vital to the flood control and rescue. However, in the practice of flood control and emergency rescue, the degree of damage caused by piping was different. It was difficult to take different measures to tackle the piping risks, which resulted in exaggeration or contempt for the rescue of piping. The main reason could be the lack of understanding of the piping damage degree. To this end, this paper presented the concept of collapsed piping based on the damage degree of piping to dike engineering, and developed a method for estimating piping damage degree using the analytic hierarchy process. And the quality of dike engineering, water head difference and piping risk characteristics were chosen as the main impact factors to evaluate the risk degree of piping. The results showed that the distance of piping to dike, with a weight value of 0.375 5, was the most important impact factor on the risk degree of piping, followed by the water level of outside dike with a weight value of 0.202 1, and piping scale had minimal effect with a weight value of 0.172 3. The risk degrees of 33 typical piping appeared in the Yangtze River, were assessed by using the analytic hierarchy process. Moreover, the two piping risks happened in Qingshan district of Wuhan city (2016) and Paizhouwan of Jiayu county, Hubei province (1998), were contrastively analyzed with the traditional empirical method and the analytic hierarchy process method, respectively, which showed that the analytic hierarchy process was more scientific and practical. The results can provide technical support for the classification of piping hazard and dike rescue.

Key words: dike engineering, piping, classification method, degree of risk