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Cai X.,Hohai University | Yan W.,Hohai University | Li Y.,Hohai University | Wu W.,Nanjing Municipal Bureau of Water Resources
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2012

Grey theory was employed to evaluate the safety risk of dyke structure and it can avoid the defects of traditional safety coefficient method. A mathematical model was built with a comprehensive evaluation index system: engineering geological conditions, regime stability, seepage stability, sliding stability, levee integrity and project management. Application of this model to practical engineering cases validated the theory and the proposed model that are useful for design of dyke rehabilitation. © Right. Source


Cai X.,Hohai University | Li Y.,Hohai University | Guo X.-W.,Hohai University | Wu W.,Nanjing Municipal Bureau of Water Resources
Water Science and Engineering | Year: 2014

Increasing frequency and severity of flooding have caused tremendous damage in China, requiring more essential countermeasures to alleviate the damage. In this study, the dynamic simulation property of a cellular automaton was used to make further progress in flood routing. In consideration of terrain's influence on flood routing, we regarded the terrain elevation as an auxiliary attribute of a two-dimensional cellular automaton in path selection for flood routing and developed a mathematical model based on a cellular automaton. A numerical case of propagation of an outburst flood in an area of the lower Yangtze River was analyzed with both the fixed-step and variable-step models. The results show that the flood does not spread simultaneously in all directions, but flows into the lower place first, and that the submerged area grows quickly at the beginning, but slowly later on. The final submerged areas obtained from the two different models are consistent, and the flood volume balance test shows that the flood volume meets the requirement of the total volume balance. The analysis of the case shows that the proposed model can be a valuable tool for flood routing. Copyright © 2014 Editorial Office of Water Science and Engineering. Source


Cai X.,State Key Laboratory of Hydrology Water Resources and Hydraulic Engineering | Cai X.,Hohai University | Li Y.,State Key Laboratory of Hydrology Water Resources and Hydraulic Engineering | Li Y.,Hohai University | And 2 more authors.
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2013

In this paper we develop a mathematical model of flood submergence based on bulk method and cellular automata theory to solve the problems of bulk method in large cycle-index, time-consuming and inaccuracy in modeling flood submergence. The calculation procedure of time step, flow rate and inundation level of breach flow is described in detail, and a case study for a typical section of Jingjiang dike is demonstrated. It is shown that this model gives satisfactory features of flood submergence in spatiotemporal variations and thus it is a useful model for design of flood warning system and emergency plans. © Copyright. Source


Cai X.,Hohai University | Li Y.,Hohai University | Wu W.,Nanjing Municipal Bureau of Water Resources | Ye S.,Nanjing Municipal Bureau of Water Resources
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2011

To consider the uncertainty of seismic effects on embankment risk factors, we simplified earthquake action into a risk factor of adverse disturbance and represented the disturbance by an attenuation function. Then we developed an analysis model of comprehensive risk under earthquake to include embankment failure risk, flooding risk and flooding area. Using this model, we analyzed the risks of flood overtopping, slope stability, seepage and soil liquefaction, and simulated the area submerged by embankment-breach flow, through a case study of Jingjiang dike's typical section under earthquakes of seven degrees. This work is useful for design of flood warning system and emergency plans. © Copyright. Source

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