Abstract. In recent years, heavy rainfall conditions have caused disasters around the world. To prevent losses by floods, levees have often been constructed in inundationprone areas. This study performed reliability analyses for the Chiuliao First Levee in southern Taiwan. The failure-related parameters were the water level, the scouring depth, and the in situ friction angle. Three major failure mechanisms were considered: the slope sliding failure of the levee and the sliding and overturning failures of the retaining wall. When the variability of the in situ friction angle and the scouring depth are considered for various flood return periods, the variations of the factor of safety for the different failure mechanisms show that the retaining wall sliding and overturning failures are more sensitive to the change of the friction angle. When the flood return period is greater than 2 years, the levee could fail with slope sliding for all values of the water level difference. The results of levee stability analysis considering the variability of different parameters could aid engineers in designing the levee cross sections, especially with potential failure mechanisms in mind.

In order to assess the reliability of circuit breaker more scientificly and effectively, a method based on improved fuzzy analytic hierarchy process and genetic algorithm is presented in this paper. Firstly circuit breaker fault tree is established according to analyzing the circuit breaker failures and which make the complex circuit breaker system failures into all kinds of basic types of failures; Secondly, Improved Fuzzy Analytic Hierarchy Process(IFAHP) is designed to analyze the fault tree, it uses the relationship between the layers of fault tree to establish fuzzy judgment matrix and convert the fuzzy consistent qualification to constrained optimization problems; Then Genetic Algorithm(GA) is adopted to get the weight of each fault which can find the optimal solution quickly and accurately; Finally, according to the practical operation of circuit breaker, high voltage circuit breaker reliability evaluation model is established to assess the reliability of circuit breaker. The analytical result of practical sample verifies the accuracy of the proposed method.

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Abstract. In recent years, heavy rainfall conditions have caused damages around the world. To prevent damages by floods, levees have often been constructed in prone-to-inundation areas. This study performed reliability analyses for the Chiuliao 1st Levee located in southern Taiwan. The failure-related parameters were the water level, the scouring depth, and the in-situ friction angle. Three major failure mechanisms were considered, including the slope sliding failure of the levee, and the sliding and overturning failures of the retaining wall. When the variabilities of the in-situ friction angle and the scouring depth are considered for various flood return periods, the variations of the factor of safety (FS) for the different failure mechanisms show that the retaining wall sliding and overturning failures are more sensitive to the variability of the friction angle. When the flood return period is greater than 2 years, the levee can undergo slope sliding failure for all values of the water level difference. The results for levee stability analysis considering the variability of different parameters could assist engineers in designing the levee cross sections, especially with potential failure mechanisms in mind.