Analysis And Application Of Block Diagram Simulation Of Earth-rockfill Dam Safety Response Under Uncertainty Conditions

Reservoirs and dams can offer multiply good purposes, such as electricitygeneration, water supply, irrigation and floods control, however, serious flooddisasters and tremendous economic losses would occur under dam break. Statisticaldata show failures of earth-rockfill dam have taken up a major part of dam failures,more than90%. Thus, this paper intends to analyze earth-rockfill dams break riskunder the failures of overtopping, seepage and instability by building the simulaitionmodel based on block diagrams under multiple factors influences. The mainachievements are summarized as followings.Firstly, a method for earth-rockfill dam safety analysis based on block diagramsimulation was presented, considering many complex factors affecting dam safetysuch as dam structure, weather conditions, reservoir levels and so on. Mathematicalmodels and block diagram models were set up successively through describing statespace of each element model of the system to determine basic variables afterdisintegrating earth-rockfill dams into independent and dynamic elements. MATLABplatform was employed to link every diagram of element models according to theirrelational models built before and the block diagram of the whole system wasachieved. The block diagram models of reservoir-tunnels-downstream river undermultiply uncertainty were built at first based on the method to lay the model basis fordams risk analysis.Secondly, the safety risk analysis calculation of dam failures under overtopping,seepage and instability was completed. Through the block diagram models offlood-reservoir-tunnels-downstream river and reservoir levels-seepage analysis andcalculation module, overtopping risk and seepage risk were presented. Taking theadvantage of Geostudio coupling analysis between seepage and slope stability,2-Dslope model coupled with seepage of earth-rockfill dam was set up to show thestability under different work conditions.Thirdly, the block diagram model of earth-rockfill dam safety respond undercoupling multiply factors on the base of models of single factor was built to realizethe whole analysis and assessment of earth-rockfill dam safety. Take flood element asthe start element, analysis the coupling mechanism between flood and seepage andbetween seepage and slope stability and set up the whole block diagram model to getthe earth-rockfill dam risk probability under the failures of overtopping, seepage and instability; with the help of fuzzy analytical hierarchy process, calculate the wholerisk probability according to each weight of overtopping, seepage and instability;furthemore, based on the dam threshold, the risk level under different failures andsecurity level of the earth-rockfill dam project were determined.