Abstract

Spatial variability and limited measurements often result in low reliability estimates of geotechnical failure modes of dikes (i.e., earthen flood defences). Required dike reinforcements are usually not executed within a few years after inception, which enables efforts to improve reliability estimates by reducing uncertainty. Often decision makers are unclear on whether uncertainty reduction is worth investing, and which (combination of) methods yields the highest Value of Information (VoI). This paper presents a framework to assess the VoI of two uncertainty reduction methods (proof loading and pore pressure monitoring) for a case study of a typical river dike with an insufficiently stable inner slope, using a decision tree. In all cases, a positive VoI was found for at least one strategy consisting of a proof load test, monitoring or both. The optimal strategy of proof loading and monitoring has a VoI of 4.0 M€, being a reduction in total cost of 25% compared to a conventional dike reinforcement. It was also found that sometimes proof loading enhances the VoI of pore pressure monitoring, which demonstrates the benefits of jointly considering different methods in a single decision tree. The decision framework yields insight in total cost and VoI of risk reduction strategies, which enables decision makers to determine where proof loading and/or pore pressure monitoring are efficient, leading to more efficient flood defence asset management.

摘要

空间可变性和有限的测量常常导致对堤坝（即土防洪堤）的岩土破坏模式的低可靠性估计。所需的堤防加固通常不会在开始后的几年内执行，这可以通过减少不确定性来提高可靠性估计。决策者通常不清楚减少不确定性是否值得投资，以及哪种（组合）方法产生最高的信息价值 (VoI)。本文提出了一个框架来评估两种不确定性降低方法（验证载荷和孔隙压力监测）的 VoI，用于使用决策树对内坡不够稳定的典型河堤进行案例研究。在所有情况下，至少有一种策略（包括验证负载测试、监控或两者兼而有之）发现了积极的 VoI。验证加载和监控的最佳策略的 VoI 为 400 万欧元，与传统的堤坝加固相比，总成本降低了 25%。还发现有时验证加载会提高孔隙压力监测的 VoI，这证明了在单个决策树中联合考虑不同方法的好处。该决策框架可以洞察风险降低策略的总成本和 VoI，使决策者能够确定验证加载和/或孔隙压力监测在哪些方面是有效的，从而实现更有效的防洪资产管理。这证明了在单个决策树中联合考虑不同方法的好处。该决策框架可以洞察风险降低策略的总成本和 VoI，使决策者能够确定验证加载和/或孔隙压力监测在哪些方面是有效的，从而实现更有效的防洪资产管理。这证明了在单个决策树中联合考虑不同方法的好处。该决策框架可以洞察风险降低策略的总成本和 VoI，使决策者能够确定验证加载和/或孔隙压力监测在哪些方面是有效的，从而实现更有效的防洪资产管理。