Structure Risk Analysis Based On Reliability Therory And Its Application In South-North Water Transfer Project

In recent years, people more and more care about the environment changes and engineering safety caused by the civil engineering and water & electricity engineering. Risks in engineering caused by many uncertainty factors which are got highly recognition. The correlative engineering risk analysis and risk management is becoming a new technique and a new trade, and this technique is gradually used in engineering practice. Statistics and Reliability theory are used as the basic theory in this paper to deal with the key and difficult questions in engineering risk analysis and risk decision area. Some important structures in South-North Water Transfer Project (SNWTP) of middle route as the engineering examples are detailed studied in the paper. The main contents researched in this paper are as follows:1. Factors that may arise the engineering risk in SNWTP of middle route are analyzed in the paper, and the possible countermeasures are put forward.2. Progress in China and overseas in reliability theory and engineering risk analysis and decision area is introduced in the paper. The relative theory is briefly described.3. "Utility" concept is introduced into the engineering area. To unify the economic and non-economic factors in engineering structures risk analysis the max expected utility value (EUV) method is presented.4. Many uncertains caused unavoidable risk in engineering planning and engineering decision. A new risk decision method is presented. The paper shows how to calculate the risk rate through reliability index, provides decision-making method based on reliability theory. Decision tree model is also used.5. Powell method is used in the paper to calculate the reliability index, this method can avoid the complexity of partial derivative calculating, and the example shows that this method is correct.6. Slope sliding risk under the stochastic water level and stochastic earthquake is studied.7. Horizontal earthquake acceleration is used in this paper for slope risk analysis; the relationship between the safety factors under the earthquake effect and non-earthquake effect is obtained. The reliability index is expressed by the safety factor. The mathematic formulation of the slope failure probability is deduced as theacceleration is stochastic. From the calculation for the real case, the influence of the earthquake is notable.8. The risk lost of the engineering structure mathematic model is established. Reviewing and summarizing the existence theory for maintenance time decision, their shortcomings are analyzed, in which the economic factor is considered more than the safety factor. So in this paper from the point of security and risk cost the natural usage limit state reliability index is put forward as the maintenance time decision rule. The right bank section of DANJIANGKOU dam of the South-North Water Transfer Project (SNWTP) as an example is analyzed to decision the maintenance time. In the end the stochastic finite element method (SFEM) is used to point out the key part for maintenance.9. The girder aqueduct structure of LI River of the SNWTP as an example is analysised for its risk. Every parts of the structure are studied; the failure modes and failure functions are established. Reliability index is calculated. Then Nonlinear SFEM is used to analysis the whole aqueduct body structure. Some availability conclusions are got.10. Some measures from the view of engineering and non-engineering are put forward in the paper to reduce the engineering risks.