Method Of Analysis For The Seepage And Erosion Reliability Of Levee Project And The Numerical Simulation Of Coastal Erosion

In the general design and analysis methods for problems of the breakwater stability, the concept of compositive safety factors is used usually. However, floodwater, storm wave and beach erosion as well as properties of soil medium are always random, which may have uncertainties. Therefore, the general method may bring disadvantages for the analysis of the breakwater stability. This paper presents a method of probability analysis in order to develop the general design and analysis methods for problems of the embankment stability under random storm wave actions as well as with random properties of the embankment medium. The major purpose of this study is carry out modellings of (1) probability analysis for the problem of seepage stability of levee projects; (2) probability analysis for the problem of erosion due to washout sediments from the embankment; (3) numerical analysis for coastal evolution due to beach erosion under energy actions of storm wave. As a practical application, the safety situation of Jiujiang dike under the 1998 pluvial condition of once a hundred years in Yangtze River has been evaluated by the reliability method from the point view of the seepage stability in terms of probability analysis and two dimensional saturated seepage finite element analysis combining with the mechanism of seepage burst in Jiujiang dike summarized in the thesis. The major reason of the seepage burst has been found from the analysis that under the 1998 pluvial condition of once a hundred years in Yangtze River, the safety reliability of Jiujiang dike against the seepage disaster is on the very low level only about 55%. Such low reliability proves that the seepage burst disaster of this dike during the flood season is inevitable under the 1998 pluvial condition. The research presents that the reliability method based on the probability analysis for seepage and erosion stability of levee project is more scientific and more reasonable for seepage safety of dikes.