The Disaster Evaluation System Of Dam-break Flood And The Research Of Dam-dam Disasters Chain For Seismic Damage Prediction

Chen Houqun who is a hydraulic expert and an academician in Chinese academyof engineering pointed out:” Strategic focus of earthquake disaster prevention of damis to prevent floods of the dam-break cause serious secondary disasters when themaximum possible earthquake occurred.Therefore, it must determine reasonably themaximum credible earthquake in the dam site and the quantitative criteria of thedesign of various types of dam-break. The two issues are the major obstacles and thefront topic which is urgently solved in the dam safety assessment, are also challengewhich must face.” It is not only geological structure is complicated in the region ofupstream Yellow River, but is an areas of high incidence of landslides. As well as itwill be induced an earthquake after reservoir storage. These may be caused hiddendanger of cascade reservoirs at the upstream Yellow River.In view of the magnitude7.3earthquake produced a secondary fault whichdislocated the ShiGang Dam is a concrete gravity dam and dam height is24.4m inNantou of Taiwan on September21,1999. In response to this event, Chen Houqunpointed out:” The ’anti-seismic’ problem of dam foundation which has few largefaults,such as ShiGang Dam,it doesn’t belong to the scope of seismic safety. Currentlyany dam is still unable to resist these kinds of disasters.” Similar to the earthquakemay also cause the collapse of the dam at the upstream Yellow River. However, forreservoir with high dam, once it should be subjected to damage of earthquake,secondary disasters which are caused by dam downstream flood peak are a lot moreserious than loss the project itself.To prevent the reservoirs is broken or once the reservoir breach is happen at theupstream of Yellow River, the protective measures can be appointed, for reducing thelosses to a minimum, in this paper, the dam-break flood of the every reservoirs at theupstream of Yellow River has been analyzed.At the upstream of Yellow River the distribution of reservoir appears cluster-likedistribution, if a dam at the up stream of Yellow River has broken, the flood mayeffect many of downstream dam with a domino cascade effect, it may lead to dam break or overflow, such as in1975, the Banqiao and Shimantan reservoir has brokenin succession, the dam-dam disaster chain has been analyzed.At the same time, the Lanzhou City, which is an important industrial city innorthwest China, has been selected as an example to estimate if one reservoir wascrashed, the effect of flood to the city. Two methods(Simplify numerical simulationmethods and Numerical simulation methods) have been used to calculate and analyzethe maximum flow of flood, the rising time of flood, maximum flow of flood arrivaltime, the reducing time of flood, the stage hydrograph of each section and theroughness of city and river.In addition, in Sangyuan gorge, the terrain is special, the backwater problems hasbeen researched preliminarily. The Lanzhou city is located at the right bank of theYellow River, but the Coriolis force was ignored in flood routing model, so theCoriolis force of flood in Lanzhou City has been estimated theoretically.