The Risk Analysis Of Seepage Stability On The Basis Of SFEM And Research Of The Reinforcement Strategy

Embankment is the most important eventual line of defence for the flood. But there are many safety problems in the current embankments. One of them is the problem of the seepage stability which has become popular and serious. Based on the stochastic finite element method (SFEM), the risk analysis has been done for the seepage stability problem with the consideration of the variability of the permeability coefficient. Then, the two-stage decision-making method is presented to study the reinforce strategy whose rule is the life cycle cost. The main contents of the dissertation are given as follows:1. The determinate finite element analysis has been done to 3-D steady seepage using modified Initial Flow Method (IFM). By using this method the unstable problem occurred in IFM can also be solved.2. The permeability coefficient is treated as the random field and is introduced directly into the functional variational formulations. Then a random variational principle and finite element method is developed with the small parameter perturbation method in the 3-D steady seepage. Furthermore, the mean and standard deviation of the water height and hydraulic gradients is presented.3. The local average method of 3-D seperatable vector stochastic field is used to separate the random field. TSFEM has been adopted to the analysis of the 3-D steady seepage. On the basis of them, risk analysis and decision-making theory are introduced to analyze the seepage stability and the related risk degree is calculated.4. The two-stage decision-making method is presented to study the reinforce strategy which can obtain the optimal risk degree and the minimum life cycle cost.5. The building cost, reinforce cost and failure cost of the embankment are comprehensively considered in this dissertation. The optimal risk level of the seepage stability is studied which rule is the minimum life cycle cost.6. The determinate finite element and SFEM analysis have been done to 3-D steady seepage of an embankment in Nanjing Qinghuai river. Then the risk degree of the embankment is calculated. Moreover, a conclusion can be obtained that the embankment needs to be reinforced. Finally, the reinforcement plan has been analyzed.