Abstract

Expert judgment plays an essential role in assessing the safety of levees, since these very long structures are generally old, few data are available for them, and they are subject to complex failure mechanisms. Expert judgement is required to assess the failure probabilities of levees when carrying out risk analysis studies. However, expert judgement is subject to biases that are highly likely to impair the quality of the probabilistic assessments obtained. This article presents a method for reducing biases in expert opinion, illustrated by its application to the case of an existing levee. Initially, the method comprises the calibration of the opinions of a panel of six experts based on the results of a quantitative analysis applied to 30 levee cross-sections for which numerical calculations were performed. It then proposes a procedure to debias expert assessments using bias correction coefficients. Regarding its application, the assessments made by the experts were debiased for 30 calibration variables. The correction coefficients obtained were then applied for the assessment of 10 variables of interest. The results show a significant reduction of biases, associated with a readjustment of the uncertainty intervals given by the experts.

摘要

专家判断在评估堤坝的安全性方面起着至关重要的作用，因为这些非常长的结构通常很旧，可用的数据很少，而且它们容易受到复杂的破坏机制的影响。在进行风险分析研究时，需要专家判断来评估堤坝的破坏概率。然而，专家判断容易受到偏差的影响，这些偏差很可能会损害所获得的概率评估的质量。本文介绍了一种减少专家意见偏差的方法，并通过其在现有堤坝案例中的应用进行了说明。最初，该方法包括根据对 30 个堤坝横截面进行数值计算的定量分析结果，对六位专家小组的意见进行校准。然后，它提出了一种使用偏差校正系数消除专家评估偏差的程序。关于其应用，专家们的评估针对 30 个校准变量进行了去偏。然后将获得的校正系数应用于评估 10 个感兴趣的变量。结果显示偏差显着减少，与专家给出的不确定区间的重新调整相关。