The Research Of System Reliability Analysis Of The Gravity Dam

In recent decades, design theory and safety evaluation of hydraulic structures based on reliability theory have being rapidly developed. However, reliability analysis is still mostly component reliability analysis. Due to actual projects, a hydraulic structure is a perplex system, and included many failure modes between which there are very complicated correlations. It has caused two difficulties in research of system reliability analysis of hydraulic structures. That are how to seek the most important failure modes and how to calculate system failure probability. On the basis of existing research results, this paper emphatically analyzes the advantages and disadvantages of different system reliability analysis methods, and studies on system reliability of complex structures with corresponding programs. According to the above work, this paper provides some references for system reliability of hydraulic structures. The main work of this paper is as follows:(1)The related non-normal distribution random variables are transformed into non-related standard normal distribution ones, and JC procedure is edited for calculating component reliability by using Matlab on this basis.(2) Summarizing previous research results, the differential equivalent recursion algorithm(DREA) and the dimensions reduction method by conditional probability(DRMCP) programs are edited in considering the relativity among the failure modes by using Matlab.(3) With two examples - system reliability analysis of the primary beam of plain steel gate and frame structure - corresponding system failure probabilities are calculated by means of the DREA and the DRMCP procedures. The above mentioned results calculated by the two approximation algorithms are compared with results obtained from the narrow bound theory. According to these results, the advantages and disadvantages, the scope of application, the existing problems are discussed.(4)The performance functions of the anti-slide stability along the direction of construction foundation surface,compressive strength of dam toe and tensile strength of dam hell with the cracks at dam hell along the direction of construction foundation surface are built by using the principle of mechanics of materials, and the reliability indexs are calculated respectively. The failure probabilities of the gravity dam by the DREA and the DRMCP on the basis of the above mentioned results. The results show that the reliabilities of the anti-slide stability along the direction of construction foundation surface,compressive strength of dam toe are decreased, but the reliability of tensile strength of dam hell are increased when there is sloping upstream face. The failure probability of the gravity dam is increased with the increasing depth of the crack, namely system reliability of the gravity dam is reduced.