| At present, there have been about 87,000 reservoirs in China, among which above 90% or so are earth dams. Most of them were built in the 1950s- 1970s(about eighty thousands), which have established firm base for water conservancy construction and took great effect for national economic development. However, the dams built during the period have worked for over thirty or forty years, some even for nearly half century, some dams has aged, including some high quality engineering. China is one of the countries which have the most amount of dams in the world and the ratio of dams failure is front-line in the world, too. Therefore, howto dispose correctly the key structure of the reservoir conservancy project-therisk questions of dams, how to consider fully and systemically all kinds of the variable characteristics in decision-making of the new engineering in safety assessment of the engineering built, and how to grasp the risk degree of each dam scientifically and reasonably is an urgent subject.Before the risk analysis of the Da Hong River earth dam, in this paper, a long series of displacement and seepage for over forty years is analysed statistically, while analysing the disciplinarians of displacement and seepage of the dam, the simulation models of displacement and seepage of the dam are established and theinfluence degree to displacement and seepage are explored by each environmentalfactor in order to make the scientific and reasonable assessment.It is well known that China is the country, which has the most amount of the earth dam throughout the world, and the same to the cases of accidents, among them, the earth dam safety is especially serious. Aiming at the characteristics of the earth dam, through the analysis of their failure modes, the risk model of earth dam failure caused by landslide, seepage and over-standard flood overtopping is founded according to the overseas and domestic statistical data. Its rationality is proved through the risk ratio analysis with the applying the Monte-Carlo method to the landslide failure -, seepage failure and flood over-standard overtopping and through P-D curve by fitting of historical and the operation period flood data of the Da Hong River and the whole risk analysis of the dam has been assessed by the width limit method. According to the existing reference, it is the first application of the risk model analysis of three items.It can be seen from the observational data analysis results of the Da Hong River earth dam that the total amount of the vertical and horizontal displacement has a trend of the stepwise increase year after year, while the increment is minishing. The displacement curve of the dam body has converged, and displacement of the dam is stable. Pore water pressure intensity loweres obviously and is coming to be steady. The water level in piezometric pipes has changed from mainly reflecting water pressure intensity during the construction and operation period to mainly reflecting seepage wetted area now. Among the factors influencing displacement and seepage of the dam, the time factor takes the greatest effect, and the reservoir water level is in succession, it answers for the general rules of the earth dam.Three items risk analysis of the Da Hong River earth dam hi the application of the risk models built hi this paper indicate that the risk ratio of landslide failure, seepage failure and flood overtopping is respectively 4.305 ×10-4,9.080×10-4 and2.246×10~2. According to the width limit method, the whole risk ratio of the dam is 2.335×10-2 |
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