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A Reliability-Based Risk Analysis of a Roller Compacted Concrete Dam – A Case Study |
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PP: 115-129 |
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doi:10.18576/amis/190110
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Author(s) |
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Zakaria Che Muda,
Mohamed Hafez,
Lariyah Mohd Sidek,
Hidayah Basri,
Zaher Almkahar,
As’ad Zakaria,
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Abstract |
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| In this paper we investigate the suitability of using first-order reliability method (FORM) analysis in design practice against a more vigorous Monte Carlo Simulation (MCS) for reliability-based analysis of the roller compacted concrete (RCC) dam in compliance with ICOLD (2005) requirements. Extreme rainfall events due to climate change critically impact the reliability and safety of the dams, making it an important consideration in dam risk analysis to prevent dam failure. A simplified first-order reliability method (FORM) with a first-order Taylor Series expansion involving a simple reliability analysis requires very little effort beyond the conventional dam stability analysis without any unfamiliar terms and can be used in routine engineering practice. Case applications to stability problems of the RCC dam against sliding and overturning modes of failures illustrate the simplicity and practical usefulness of the method. The sliding failure was the dominant failure mode then the overturning failure with the friction angle influential random variable has the highest sensitivity of 90.6% and lastly density of concrete with only 9.4%. A strong linear correlation between the reliability index and the factor of safety for sliding has been established. An excellent linear correlation between the FORM-Taylor Series and Monte Carlo analysis for sliding has been obtained. The overturning failure mode has the least significant effect where its probability of failure is almost nil as compared with the sliding mode of failure. The Taylor Series method is based on a simplified first-order probabilistic analysis, although somewhat conservative but adequate to be used in design stage whereas the Monte Carlo method provides a more rigorous and precise form of analysis suited for the construction and operation stages to be used in practice. The unconditional and conditional (combined) probability of failure for different modes of failure for all the scenarios were evaluated against the ICOLD (2005) requirements.
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