Risk Analysis Of Stability Of Channel Slopes For Inter-Basin Water Transfer Project

According to the method of risk analysis, the analytic process include risk distinguishing, risk estimating and risk evaluating. Firstly, the paper finds the fundamental accident that leads to landslide of the channel slope by drawing accident tree and the consequence of the losses after slope instability. Secondly, slope Instability risk is divided into two parts: failure probability and consequence of the losses that can be figured out by established the calculation model, certain calculation method and calculation steps. Finally, mathematical equation of risk degree is established by synthetically taking the failure probability and the losses into account, and puts forward the allowed standard of risk which provides scientific basis for risk evaluation and decision of channel slope.In this paper, the Monte-Carlo method is applied to analyze the reliability of channel slope stability because of the high-nonlinear limit state equation. For circle failure surface, this paper uses Genetic Algorithm's theory to search for critical slip surface which the reliability index of the slope stability is minimum. Because the objective function of the reliability index is nonconvex, multi-variable, and existing many minimums. Genetic algorithm is provided as a powerful tool that is a global optimization method, which can overcome the drawbacks of local optimum widely existing in classic searching method. Combining Monte-Carlo method with Genetic Algorithm's theory, the composite importance sampling technique is used, which can increase the calculation efficiency.Loss of life, society-economic loss and resources-environment loss are redivided into people's life loss, the direct economic loss and indirect economic loss. The paper discusses the calculation methods of the three kinds of losses. On the basis of value accounting theory, input-output theory and capitalization theory of ability to obtain individual income, the different calculation models are established.Applying the theories and methods of risk analysis in slope stability to the case of channel slopes for the middle route of the south-to-north water transfer project, this paper considers the four conditions of normal circumstance, infiltration of rainfall, water level's sharply descending and earthquake action which lead to the landslide of channel slope by risk distinguishing, and works out the risk degree of channel slope instability. At last, this paper puts forward the allowed standard of risk-reliability index to be used for risk analysis ofchannel slope by combining research achievements from both domestic and foreign with engineering practices/According to the standard of risk-allowed reliability index, the application of the study conclusions into the practice was explored.