| 1. |
- Merisalu, Johanna, 1990, et al.
(författare)
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Probabilistic cost-benefit analysis for mitigating hydrogeological risks in underground construction
- 2023
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798. ; 131
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Tidskriftsartikel (refereegranskat)abstract
- Leakage of groundwater into underground facilities can subsequently cause groundwater drawdown, subsidence and subsidence damages to the built-up environment. In order to reduce the risk of damage, measures to mitigate the risks must often be implemented. The aim of this paper is to describe and demonstrate a probabilistic cost-benefit analysis approach to assess the economic profitability of investing in different risk mitigation alternatives. Since underground construction is always associated with uncertainties, the analysis uses probability distribution functions for uncertain parameters and Monte Carlo simulations to quantify probabilities of damage and implementation costs. The proposed approach is exemplified with a case study, the road tunnel project Bypass (Förbifart) Stockholm in eastern Sweden, for which four risk mitigation alternatives were evaluated. In conclusion, the approach helps to highlight the economic effects of different risk mitigation approaches and constitute a transparent support for decisions on implementation of risk mitigation. For the case study, the analysis indicates that the implementation costs of ∼ 7000 MSEK (700 million EUR) for risk mitigation needed to fulfil the legal requirements, from the Swedish Land- and Environmental court, in the form of ambitious sealing strategies are disproportionate relative to the benefits of ∼ 50 MSEK (5 million EUR) gained in the form of reduced damage risk for the built-up environment. In other words, billions SEK of taxpayers' money are spent on unnecessary expenses to fulfill legal requirements without societal benefits. The novelty of the paper constitutes the coupling of models and combination of established methods for management of hydrogeological risks.
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| 2. |
- Wikby, Pierre, 1995, et al.
(författare)
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The influence of parameter variability on subsidence
- 2023
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Ingår i: 10th European Conference on Numerical Methods in Geotechnical Engineering. ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Leakage into rock tunnels covered by thick soft clay deposits may cause a pore water pressure drop over large areas through underdrainage, resulting in settlement problems and potential damage to structures. In urban areas, heterogeneity in soil properties can be substantial. In this paper, a case study with a systematic sensitivity analysis combined with coupled hydro-mechanical finite element analyses was performed for three key parameters (overconsolidation ratio, vertical hydraulic conductivity and hydraulic anisotropy) considering one scenario of underdrainage. The results show that both the magnitude and uncertainty of settlements are strongly stratigraphy-dependent. The overconsolidation ratio contributed the most to the settlement uncertainty and the effect of vertical hydraulic conductivity was also found to be significant, while the changes in hydraulic anisotropy had negligible influence.
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