Advances on the Failure Analysis of the Dam-Foundation Interface of Concrete Dams

[EN] Failure analysis of the dam-foundation interface in concrete dams is characterized by complexity, uncertainties on models and parameters, and a strong non-linear softening behavior. In practice, these uncertainties are dealt with a well-structured mixture of experience, best practices and prudent, conservative design approaches based on the safety factor concept. Yet, a sound, deep knowledge of some aspects of this failure mode remain unveiled, as they have been offset in practical applications by the use of this conservative approach. In this paper we show a strategy to analyse this failure mode under a reliability-based approach. The proposed methodology of analysis integrates epistemic uncertainty on spatial variability of strength parameters and data from dam monitoring. The purpose is to produce meaningful and useful information regarding the probability of occurrence of this failure mode that can be incorporated in risk-informed dam safety reviews. In addition, relationships between probability of failure and factors of safety are obtained. This research is supported by a more than a decade of intensive professional practice on real world cases and its final purpose is to bring some clarity, guidance and to contribute to the improvement of current knowledge and best practices on such an important dam safety concern.This paper was published with the support of the research project "INICIA" (Methodology for Assessing Investments on Water Cycle Infrastructures informed on Risk and Energy Efficiency Indicators, BIA2013-48157-C2-1-R, 2014-2016), co-funded by the Spanish Ministry of Economy and Competitiveness "Ministerio de Economia y Competitividad" (Programa Estatal de Investigacion, Desarrollo e Innovacion Orientada a los Retos de la Sociedad) and the European Regional Development Fund (ERDF).Altarejos García, L.; Escuder Bueno, I.; Morales Torres, A. (2015). Advances on the Failure Analysis of the Dam-Foundation Interface of Concrete Dams. Materials. 8(12):8255-8278. https://doi.org/10.3390/ma8125442S8255827881

Contribución a la estimación de la probabilidad de fallo de presas de hormigón en el contexto del análisis de riesgos

Las metodologías de análisis de riesgos precisan cuantificar el riesgo, lo que en general implica estimar, para un determinado estado inicial del sistema presa-embalse, y para los diversos modos de fallo, tanto la probabilidad de los eventos de solicitación como la probabilidad condicional de la respuesta del sistema presa-embalse dado un determinado evento de solicitación, así como estimar las consecuencias sobre el medio, dada una determinada respuesta del sistema. Fraccionado así el problema, la presente tesis doctoral se centra en el estudio de la segunda de las probabilidades expuesta, es decir, en la cuantificación de la probabilidad condicional de la respuesta del sistema, dado un determinado evento de solicitación, y para el caso particular de presas de hormigón. En el contexto del análisis de riesgos, para obtener esta probabilidad se dispone de tres métodos: referencias históricas, emisión de probabilidades y, finalmente, técnicas de análisis basadas en fiabilidad. La cuestión de la estimación de las probabilidades de la respuesta de un sistema complejo como el sistema presa-embalse ha estado sujeta desde los inicios del análisis de riesgos a controversia y discusión por parte de la comunidad presística. Con este escenario de partida, se presenta en esta tesis doctoral una metodología para mejorar y dotar de mayor robustez a la estimación de la probabilidad condicional de la respuesta del sistema presa-embalse, para el caso de presas de hormigón, que incorpora el empleo de modelos de comportamiento complejos mediante técnicas de simulación numérica, sobre los cuales se aplican técnicas de fiabilidad de diversos niveles de exactitud, y, en particular, técnicas de fiabilidad Nivel 3, mediante simulaciones por el método de Monte Carlo. La variabilidad espacial y temporal de las variables (acciones y propiedades de los materiales) y la incertidumbre inherente a los mismos se considera mediante las correspondientes funciones de probabilidad.Altarejos García, L. (2009). Contribución a la estimación de la probabilidad de fallo de presas de hormigón en el contexto del análisis de riesgos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/7350Palanci

Building fragility curves of sliding failure of concrete gravity dams integrating natural and epistemic uncertainties

[EN] The proposed procedure combines the concepts of the Electrical Power Research Institute (EPRI) guidelines to develop fragility curves for the nuclear industry with existing reliability techniques for computing fragility curves in the context of concrete dams engineering. The procedure has been applied to a dam to illustrate how it can be used in a real case in such a manner that fragility curves are obtained integrating natural and epistemic uncertainties without losing track of their separate contribution to risk results. (C) 2016 Elsevier Ltd. All rights reserved.This paper was published with the support of the research project "INICIA" (Methodology for Assessing Investments on Water Cycle Infrastructures informed on Risk and Energy Efficiency Indicators, BIA2013-48157-C2-1-R, 2014-2016), co-funded by the Spanish Ministry of Economy and Competitiveness "Ministerio de Economia y Competitividad" (Programa Estatal de Investigacion, Desarrollo e Innovation Orientada a los Retos de la Sociedad) and the European Regional Development Fund (ERDF).Morales Torres, A.; Escuder Bueno, I.; Altarejos García, L.; Serrano Lombillo, AJ. (2016). Building fragility curves of sliding failure of concrete gravity dams integrating natural and epistemic uncertainties. Engineering Structures. 125:227-235. https://doi.org/10.1016/j.engstruct.2016.07.006S22723512

Fisher information of special functions and second-order differential equations

We investigate a basic question of information theory, namely the evaluation of the Fisher information and the relative Fisher information with respect to a nonnegative function, for the probability distributions obtained by squaring the special functions of mathematical physics which are solutions of second-order differential equations. Emphasis is made in the Nikiforov-Uvarov hypergeometric-type functions. We obtain explicit expressions for these information-theoretic properties via the expectation values of the coefficients of the differential equation. We illustrate our approach for various special functions of physico-mathematical interest

Del relativismo cultural al etnocentrismo (y vuelta)

Frente a la realidad de un mundo globalizado, pueden surgir dos actitudes que van en detrimento de una comunicación interpersonal fructífera entre personas de diversas culturas. Se trata del etnocentrismo y del relativismo cultural, a menudo presentadas como opuestas y contradictorias. En el presente trabajo, se intenta probar que el etnocentrismo puede ser consecuencia de un relativismo cultural radical. Se dan razones de por qué ambos han de ser evitados y se propone un sentido no radical de “relativismo cultural” que ayudaría a la comprensión de otras culturas. También se tocan cuestiones de moral relacionada

Condition assessment of water infrastructures: application to Segura river basin (Spain)

The paper deals with the condition assessment of water management infrastructures such as storage facilities, water mains and water distribution facilities. The objective is to develop a methodology able to provide a fast, simple assessment of present asset condition, that can also be used for predicting future conditions under different investment scenarios. The authors investigate the use of different methodologies to assess condition with focus on simple, indirect condition indices based on maintenance records, such as Infrastructure Value Index (IVI) and Asset Sustainability Index (ASI). The novelty of the approach presented is the development of a methodology that combines an asset inventory together with maintenance data, that can be integrated hierarchically, delivering an assessment of condition of elements, assets and groups of assets in a bottom-up fashion. The methodology has been applied to a group of water management infrastructures of the Segura River Basin in Spain. The main conclusion is that the proposed methodology allows to assess assets' sustainability based upon past and current trends in operation and maintenance budgets, providing a baseline for planning future maintenance actions.This research received no external funding

A new risk reduction indicator for dam safety management combining efficiency and equity principles

[EN] Large dams are critical infrastructures whose failure could produce high economic and social consequences. Risk analysis has been shown to be a suitable methodology to assess these risks and to inform dam safety management. In this sense, risk reduction indicators are a useful tool to manage risk results, yielding potential prioritisation sequences of investments in dams portfolios. Risk management is usually informed by two basic principles: efficiency and equity. These two principles many times conflict, requiring a tradeoff between optimising the expenditures and providing a high level of protection to all individuals. In this paper, the risk reduction indicator Equity Weighted Adjusted Cost per Statistical Life Saved (EWACSLS) is presented. This indicator allows obtaining prioritisation sequences of investments while maintaining an equilibrium between equity and efficiency principles. In order to demonstrate its usefulness, it has been applied in a real-world case study, a portfolio of 27 dams where 93 structural and non-structural investments are prioritised. The EWACSLS indicator is analysed in detail and its results are compared with other existing risk reduction indicators, showing its flexibility and how it can be a very well balanced indicator for the purpose of prioritisation of risk reduction measures.This paper was published with the support of the research project ‘INICIA’ (Methodology for Assessing Investments on Water Cycle Infrastructures informed on Risk and Energy Efficiency Indicators, BIA2013-48157-C2- 1-R, 2014-2016); co-funded by the Spanish Ministry of Economy and Competitiveness ‘Ministerio de Economía y Competitividad’ (Programa Estatal de Investigación, Desarrollo e Innovación Orientada a los Retos de la Sociedad); and the European Regional Development Fund (ERDF).Serrano Lombillo, AJ.; Morales Torres, A.; Escuder Bueno, I.; Altarejos García, L. (2016). A new risk reduction indicator for dam safety management combining efficiency and equity principles. Structure and Infrastructure Engineering. 13(9):1157-1166. https://doi.org/10.1080/15732479.2016.1245762S11571166139Blackorby, C., & Donaldson, D. (1977). Utility vs equity. Journal of Public Economics, 7(3), 365-381. doi:10.1016/0047-2727(77)90055-xBleichrodt, H. (1997). Health utility indices and equity considerations. Journal of Health Economics, 16(1), 65-91. doi:10.1016/s0167-6296(96)00508-5De Blaeij, A., Florax, R. J. G. ., Rietveld, P., & Verhoef, E. (2003). The value of statistical life in road safety: a meta-analysis. Accident Analysis & Prevention, 35(6), 973-986. doi:10.1016/s0001-4575(02)00105-7(2001). The Economic Journal, 111(471). doi:10.1111/ecoj.2001.111.issue-471Dolan, P. (1998). The measurement of individual utility and social welfare. Journal of Health Economics, 17(1), 39-52. doi:10.1016/s0167-6296(97)00022-2Dundar, H. (1999). Equity, quality and efficiency effects of reform in Turkish higher education. Higher Education Policy, 12(4), 343-366. doi:10.1016/s0952-8733(99)00016-1Jonkman, S. N., van Gelder, P. H. A. J. M., & Vrijling, J. K. (2003). An overview of quantitative risk measures for loss of life and economic damage. Journal of Hazardous Materials, 99(1), 1-30. doi:10.1016/s0304-3894(02)00283-2Joshi, N. N., & Lambert, J. H. (2007). Equity Metrics With Risk, Performance, and Cost Objectives for the Prioritization of Transportation Projects. IEEE Transactions on Engineering Management, 54(3), 539-547. doi:10.1109/tem.2007.900790(1997). Risk Analysis, 17(4). doi:10.1111/risk.1997.17.issue-4Khadam, I. M., & Kaluarachchi, J. J. (2003). Multi-criteria decision analysis with probabilistic risk assessment for the management of contaminated ground water. Environmental Impact Assessment Review, 23(6), 683-721. doi:10.1016/s0195-9255(03)00117-3Linnerooth-Bayer, J., & Amendola, A. (2000). Global Change, Natural Disasters and Loss-sharing: Issues of Efficiency and Equity. Geneva Papers on Risk and Insurance - Issues and Practice, 25(2), 203-219. doi:10.1111/1468-0440.00060(1999). Economic Inquiry, 37(4). doi:10.1111/ecin.1999.37.issue-4Morales-Torres, A., Serrano-Lombillo, A., Escuder-Bueno, I., & Altarejos-García, L. (2016). The suitability of risk reduction indicators to inform dam safety management. Structure and Infrastructure Engineering, 1-12. doi:10.1080/15732479.2015.1136830(2011). Risk Analysis, 31(6). doi:10.1111/risk.2011.31.issue-6Stewart, M. G., & Mueller, J. (2008). A risk and cost-benefit assessment of United States aviation security measures. Journal of Transportation Security, 1(3), 143-159. doi:10.1007/s12198-008-0013-0Yamano, N., & Ohkawara, T. (2000). The Regional Allocation of Public Investment: Efficiency or Equity? Journal of Regional Science, 40(2), 205-229. doi:10.1111/0022-4146.0017

Empirical Tool for the Assessment of Annual Overtopping Probabilities of Dams

[EN] This paper presents a simple tool for the assessment of maximum overtopping probabilities of dams. The tool is based on empirical relations between the overtopping probability and the basic hydrological and hydraulic characteristics of the dam-reservoir system: the unit storage capacity, VF*, and the unit spillway capacity, QCap*, both weighted with the relative importance of the 1,000-year flood. The surface issued from the tool represents the limit above which no VF*-QCap* combination is statistically expected to offer a higher probability. The tool was calibrated using the detailed overtopping models of 342,233 synthetic cases generated from 30 existing dams and then validated against a set of 21 independent cases. The tool is useful when analyzing a portfolio of dams in previous screening phases of dam risk analysis. It aims at identifying overtopping as a relevant failure mode and easily classifying each dam in terms of its overtopping probability. The tool is also a support for the definition and prioritization of corrective measures since it assesses their impact in the overtopping probability reduction.Fluixá-Sanmartín, J.; Altarejos-García, L.; Morales-Torres, A.; Escuder Bueno, I. (2019). Empirical Tool for the Assessment of Annual Overtopping Probabilities of Dams. Journal of Water Resources Planning and Management. 145(1):1-12. https://doi.org/10.1061/(ASCE)WR.1943-5452.0001017S112145

The suitability of risk reduction indicators to inform dam safety management

[EN] Risk analysis can provide very suitable and useful information to manage the safety of critical civil infrastructures. Indeed, results of quantitative risk models can be used to inform prioritisation of safety investments on infrastructures' assets and portfolios. In order to inform this prioritisation, a series of risk reduction indicators can be used. This paper reviews existing indicators for dam safety, tracks how equity and efficiency principles are captured, propose additional indicators and provides insights into how tolerability guidelines and benefit-cost analysis can also play a role in decision-making. All reviewed, analysed and/or combined indicators are later applied in a case study, a portfolio of 27 dams where 93 structural and non-structural investments are prioritised. The case study shows that prioritisation sequences based on risk model results provide suitable and useful information, acknowledging that other concerns may be conditioning decision-making processes. With the results of the case study, a full comparison between all studied risk reduction indicators is made, and three indexes are calculated for all of them to measure how close they are to a theoretical best.The Spanish Ministry of Economy and Competitiveness (MINECO) has supported the work described in this paper through the research project entitled IPRESARA (Incorporating man-made risk components into general dam risk management [BIA 2010-17852]) within the period 2011-2013 and the project INICIA (Methodology for assessing investments on water cycle infrastructures informed on risk and energy efficiency indicators [BIA 2013-48157-C2-1-R]) within the period 2014-2016.Morales Torres, A.; Serrano Lombillo, AJ.; Escuder Bueno, I.; Altarejos García, L. (2016). The suitability of risk reduction indicators to inform dam safety management. Structure and Infrastructure Engineering. 12(11):1465-1476. https://doi.org/10.1080/15732479.2015.1136830S146514761211Ayyub, B. M., McGill, W. L., & Kaminskiy, M. (2007). Critical Asset and Portfolio Risk Analysis: An All-Hazards Framework. Risk Analysis, 27(4), 789-801. doi:10.1111/j.1539-6924.2007.00911.xBaecher, G. B., Paté, M. E., & De Neufville, R. (1980). Risk of dam failure in benefit-cost analysis. Water Resources Research, 16(3), 449-456. doi:10.1029/wr016i003p00449Bohnenblust, H. (1998). Risk-Based Decision Making in the Transportation Sector. Quantified Societal Risk and Policy Making, 132-153. doi:10.1007/978-1-4757-2801-9_14Bottelberghs, P. . (2000). Risk analysis and safety policy developments in the Netherlands. Journal of Hazardous Materials, 71(1-3), 59-84. doi:10.1016/s0304-3894(99)00072-2De Blaeij, A., Florax, R. J. G. ., Rietveld, P., & Verhoef, E. (2003). The value of statistical life in road safety: a meta-analysis. Accident Analysis & Prevention, 35(6), 973-986. doi:10.1016/s0001-4575(02)00105-7Ellingwood, B. R. (2005). Risk-informed condition assessment of civil infrastructure: state of practice and research issues. Structure and Infrastructure Engineering, 1(1), 7-18. doi:10.1080/15732470412331289341Figueira, J., Greco, S., & Ehrogott, M. (2005). Multiple Criteria Decision Analysis: State of the Art Surveys. International Series in Operations Research & Management Science. doi:10.1007/b100605Jonkman, S. N., Jongejan, R., & Maaskant, B. (2010). The Use of Individual and Societal Risk Criteria Within the Dutch Flood Safety Policy-Nationwide Estimates of Societal Risk and Policy Applications. Risk Analysis, 31(2), 282-300. doi:10.1111/j.1539-6924.2010.01502.xJonkman, S. N., van Gelder, P. H. A. J. M., & Vrijling, J. K. (2003). An overview of quantitative risk measures for loss of life and economic damage. Journal of Hazardous Materials, 99(1), 1-30. doi:10.1016/s0304-3894(02)00283-2Joshi, N. N., & Lambert, J. H. (2007). Equity Metrics With Risk, Performance, and Cost Objectives for the Prioritization of Transportation Projects. IEEE Transactions on Engineering Management, 54(3), 539-547. doi:10.1109/tem.2007.900790Kabir, G., Sadiq, R., & Tesfamariam, S. (2013). A review of multi-criteria decision-making methods for infrastructure management. Structure and Infrastructure Engineering, 10(9), 1176-1210. doi:10.1080/15732479.2013.795978Kaplan, S. (1997). The Words of Risk Analysis. Risk Analysis, 17(4), 407-417. doi:10.1111/j.1539-6924.1997.tb00881.xKeeney, R. L., & Raiffa, H. (1993). Decisions with Multiple Objectives. doi:10.1017/cbo9781139174084Khadam, I. M., & Kaluarachchi, J. J. (2003). Multi-criteria decision analysis with probabilistic risk assessment for the management of contaminated ground water. 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Management of River Basin Physical Assets

River basin management involves, among other activities, the operation, maintenance and renewal of existing water and wastewater physical infrastructure assets, as well as the planning, designing, procurement and construction of new water infrastructure assets, in order to provide and secure present and future water demand, and other services, such as flood control and mitigation. Focus is set on increasing demand issues and uncertainty in available resources due to climate change. But there is a challenge also in the management of an aging portfolio of critical infrastructures, including storage, diversion and flood protection facilities, water wells, water conveyance facilities and wastewater treatment plants. Though physical asset management methodologies are well developed and established, such as ISO 55001, their application to infrastructures managed by river basin authorities is not widespread. This chapter presents key components for effective management covering the following aspects: asset monetary valuation; asset condition assessment; estimation of risks linked with asset condition; planning and prioritization of capital and maintenance expenditures; and expected impacts on water tariffs. A raw water distribution system in the Segura River Basin in Spain has been used as case study