Reliability assessment of quay wall renewal method Koningsgracht
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Abstract
This study focuses on the assessment of the reliability of the geobag wall system within the context of the Koningsgracht renewal project. The objective is to identify and understand the most sensitive phase during the project’s execution by conducting a comprehensive probabilistic analysis.
The geobag wall, a temporarily constructed component of Koningsgracht, emerges as the focal point of sensitivity in this study. Unlike other project elements, such as historic structures and conventional engineering components, the geobag wall possesses unique characteristics, notably its composition of individual geobags and the use of jute geotextile, which could result into individual instability.
The research delves into the analysis of failure mechanisms and limit states for the geobag wall, considering both the monolithic structure and potential local failures within its segments. The failure modes found include horizontal sliding, overturning and the rupture of the geotextile. Various parameters are examined to calculate factors of safety. To account for uncertainties inherent in geological and structural parameters, probabilistic methods are employed. Monte Carlo simulation and the First-Order-Second-Moment (FOSM) method are utilized to model the behavior of the geobag wall under different scenarios, encompassing a wide range of parameter combinations.
Correlations between parameters are introduced to simulate spatial variability, ensuring that the values of geological and structural factors align reasonably with one another. This approach reflects the real-world complexities of geotechnical systems. The analysis reveals intriguing results, with factors such as friction angle playing a significant role in horizontal sliding and overturning, while textile rupture remains relatively independent of geological parameters and heavily reliant on tensile strength of the jute geotextile. Additionally, wall dimensions, particularly height and width, are found to
exert a substantial influence on various failure modes.
Ultimately, the probabilistic analysis yields insights into the reliability of the geobag wall system. The study indicates a 1.625 · 10−4 probability of failure for the geobag wall system considering a Factor of Safety (FOS) of 1.0, aligning with the overall reliability of the Koningsgracht renewal method.