In flood control dams it is not only the failure to prevent flood larger than their design carrying capacity, but also the uncertainties of hydraulic factors that cause disasters. In general, the hydraulic risk is not...In flood control dams it is not only the failure to prevent flood larger than their design carrying capacity, but also the uncertainties of hydraulic factors that cause disasters. In general, the hydraulic risk is not considered in most of the hydrological analysis in floodproofing plan and design. In this paper, a method of evaluating the hydraulic risk is developed by employing risk theory, and the concept can easily be extended to other types of risk analysis. As a result, it is possible not to consider the hydraulic resks when the design hydrologic risk of flood control dam is lger. Otherwise, the hydraulic risks must be noticed. The research is very helpful for the development of the flood control theory used at present.展开更多
The frequency of large dam failures all over the world, with a high toll of lives lost, pinpoints the still unsolved problems of flood risk resulting from the presence of large dams in built-up areas. Some of these fa...The frequency of large dam failures all over the world, with a high toll of lives lost, pinpoints the still unsolved problems of flood risk resulting from the presence of large dams in built-up areas. Some of these failures and other related incidents took place in Italy in the past century. The purpose of this paper is to discuss the three worst cases of dam failures occurring in Italy, analyzing the causes which led to collapse. They are the dams of Gleno （1923）, Molare （1935） and Stava （1985）.展开更多
The loss of life risk evaluation model for dam break is built in this paper.By using an improved Monte Carlo method,the overtopping probability induced by concurrent flood and wind is calculated,and the Latin Hypercub...The loss of life risk evaluation model for dam break is built in this paper.By using an improved Monte Carlo method,the overtopping probability induced by concurrent flood and wind is calculated,and the Latin Hypercube Sampling is used to generate random numbers.The Graham method is used to calculate the loss of life resulting from dam failure.With Dongwushi reservoir located at Hebei Province taken as an example,the overtopping probability induced by concurrent flood and wind is calculated as 4.77×10-6.Los...展开更多
Dams are critical and essential elements in any infrastructure and, in front of accidents occurred in many countries, it is extremely important to know the risk of these structures. Inserted in this context, it was fo...Dams are critical and essential elements in any infrastructure and, in front of accidents occurred in many countries, it is extremely important to know the risk of these structures. Inserted in this context, it was found in the technical literature, methods and tools capable of measuring the exposure value by means of indicators. In the study, the highlights were 12 methods of qualitative, semiquantitative and quantitative risk analysis, representing an overview of risk analysis methods available in the literature with potential use in dams, that it has been done into electronic spreadsheets. The case study is performed on a sample of concrete dam and earth/rockfill built and operated by Eletrobr^s Furnas Company, supported by documentary research, projects, field inspections and interviews with experts. After applying the methods and the analysis thereof, has been prepared the Eletrobras Fumas dam risk analysis method which is characterized by adapting the criteria analyzed to the reality of the company＇s dams and it was also performed the portfolio risk analysis of 18 dams. In spite of the variety and subjectivity of qualitative and semiquantitative methods, the results show that they tend to converge on the analysis of dam based on risk. The application methodology demonstrates the feasibility assessment stage, covering the preliminary analysis for portfolio dams, followed by formal and individual risk analyzes for the most critical structures. These results confirm the applicability of risk analysis techniques, contributing to the consolidation of this toot as fundamental in the dam safety.展开更多
Gradual shift has been observed lately of dam safety procedures from the conventional technical based towards a wider scope of risk management procedure based on risk analysis. The new approach considers the likelihoo...Gradual shift has been observed lately of dam safety procedures from the conventional technical based towards a wider scope of risk management procedure based on risk analysis. The new approach considers the likelihood level of occurrence of a multitude of hazards and the magnitude of the resulting possible consequences in case of failure using rational cause and effect arguments. Most dam owners are shifting towards the use of the new risk based procedures; and even governments themselves are moving towards formalizing the new trend. Legislations in the United States were promulgated [1] after serious dam failures and the adoption of stringent levels of scrutiny led such federal dam owners to pioneer in this field and in developing the concepts and methods required. The comer stone in risk analysis is the definition of the potential modes that may lead to failure and assessment of the likelihood levels of their occurrence and possible category of the consequences which, after thorough evaluation, will shape the decision making. This type of analysis was applied to Mosul Dam as a case study and resulted in definite recommendations.展开更多
It is of great importance to establish the dam failure risk criteria for dam risk assessment and management. Presently, the F-N curve method is widely applied in practice, in which the F-N curves are used for establis...It is of great importance to establish the dam failure risk criteria for dam risk assessment and management. Presently, the F-N curve method is widely applied in practice, in which the F-N curves are used for establishing the criteria for separate risks caused by the dam failure in life, economy, environment, and society respectively. In this paper, in consideration of the overlying effect by two or more types of risk losses resulting from the dam failure at the same time, the F-N curved surface method is presented for establishing the integrated dam failure risk criteria. In this method, the named F-N curved surfaces are established, and by these curved surfaces, the acceptable, the allowable, and the unallowable integrated risk zones can be defined.展开更多
This paper discusses the methods of establishing risk criteria for dams and reviews the application of dam risk criteria for individuals and societies in different countries or districts. Given the conditions in China...This paper discusses the methods of establishing risk criteria for dams and reviews the application of dam risk criteria for individuals and societies in different countries or districts. Given the conditions in China and considering the public safety and acceptance of dam risk, historical dam break data and current design standards, individual and societal risk criteria for dams are proposed. The tolerable dam risk criteria for individuals should be set to 10-5-10-7 per annum based on project scale, for ex- ample, approximately 1.0xl0 7 per annum, which corresponds to a reliability index of 4.2 based on a 100-year lifespan for a first-class or large project. The societal limit for risk tolerance for dams should be set to approximately 10-3-10-5 per annum, corresponding to the fatality range from 1 to 100 and be horizontally extended to 1000, and F-N curves are proposed. It was also found that the reliability indices of Chinese Standard （GB 50199-2013） and Eurocodel （2002） are different, but they have the same level of safety measured by the annual probability of failure. The research results have significance for establishing dam risk criteria.展开更多
The applied technology of high roller-compacted concrete(RCC) dams is quite complicated because of various risk factors, including the weather condition, supply of concrete aggregate, efficiency of transport machinery...The applied technology of high roller-compacted concrete(RCC) dams is quite complicated because of various risk factors, including the weather condition, supply of concrete aggregate, efficiency of transport machinery and dam surface machinery, and so on. In order to ensure the comprehensiveness, accuracy and objectivity of construction schedule risk analysis, a mathematical model called improved correlated schedule risk analysis model(CSRAM) is proposed in this paper. This model takes into account not only the construction features of high RCC dams, but also the stochastic variations of risk factors with the construction schedule, as well as their comprehensive effects. Using Monte Carlo method to solve this model enables the completion probability of a high RCC dam construction within plan time, and uncertainty analysis of risk factors. Compared with the conventional CSRAM, the improved CSRAM has higher completion probability and more convergent distribution of a simulation period, making analysis results more accurate and closer to actual engineering conditions. Among the ten risk factors selected, efficiency of dam surface machinery and proficiency of workers are found to be of the maximum uncertainty.展开更多
文摘In flood control dams it is not only the failure to prevent flood larger than their design carrying capacity, but also the uncertainties of hydraulic factors that cause disasters. In general, the hydraulic risk is not considered in most of the hydrological analysis in floodproofing plan and design. In this paper, a method of evaluating the hydraulic risk is developed by employing risk theory, and the concept can easily be extended to other types of risk analysis. As a result, it is possible not to consider the hydraulic resks when the design hydrologic risk of flood control dam is lger. Otherwise, the hydraulic risks must be noticed. The research is very helpful for the development of the flood control theory used at present.
文摘The frequency of large dam failures all over the world, with a high toll of lives lost, pinpoints the still unsolved problems of flood risk resulting from the presence of large dams in built-up areas. Some of these failures and other related incidents took place in Italy in the past century. The purpose of this paper is to discuss the three worst cases of dam failures occurring in Italy, analyzing the causes which led to collapse. They are the dams of Gleno （1923）, Molare （1935） and Stava （1985）.
基金Supported by Tianjin Natural Science Foundation(No.08JCZDJC25400,No.09JCYBJC08700)Major State Basic Research Development Program of China ("973" Program,No.2007CB714101)
文摘The loss of life risk evaluation model for dam break is built in this paper.By using an improved Monte Carlo method,the overtopping probability induced by concurrent flood and wind is calculated,and the Latin Hypercube Sampling is used to generate random numbers.The Graham method is used to calculate the loss of life resulting from dam failure.With Dongwushi reservoir located at Hebei Province taken as an example,the overtopping probability induced by concurrent flood and wind is calculated as 4.77×10-6.Los...
文摘Dams are critical and essential elements in any infrastructure and, in front of accidents occurred in many countries, it is extremely important to know the risk of these structures. Inserted in this context, it was found in the technical literature, methods and tools capable of measuring the exposure value by means of indicators. In the study, the highlights were 12 methods of qualitative, semiquantitative and quantitative risk analysis, representing an overview of risk analysis methods available in the literature with potential use in dams, that it has been done into electronic spreadsheets. The case study is performed on a sample of concrete dam and earth/rockfill built and operated by Eletrobr^s Furnas Company, supported by documentary research, projects, field inspections and interviews with experts. After applying the methods and the analysis thereof, has been prepared the Eletrobras Fumas dam risk analysis method which is characterized by adapting the criteria analyzed to the reality of the company＇s dams and it was also performed the portfolio risk analysis of 18 dams. In spite of the variety and subjectivity of qualitative and semiquantitative methods, the results show that they tend to converge on the analysis of dam based on risk. The application methodology demonstrates the feasibility assessment stage, covering the preliminary analysis for portfolio dams, followed by formal and individual risk analyzes for the most critical structures. These results confirm the applicability of risk analysis techniques, contributing to the consolidation of this toot as fundamental in the dam safety.
文摘Gradual shift has been observed lately of dam safety procedures from the conventional technical based towards a wider scope of risk management procedure based on risk analysis. The new approach considers the likelihood level of occurrence of a multitude of hazards and the magnitude of the resulting possible consequences in case of failure using rational cause and effect arguments. Most dam owners are shifting towards the use of the new risk based procedures; and even governments themselves are moving towards formalizing the new trend. Legislations in the United States were promulgated [1] after serious dam failures and the adoption of stringent levels of scrutiny led such federal dam owners to pioneer in this field and in developing the concepts and methods required. The comer stone in risk analysis is the definition of the potential modes that may lead to failure and assessment of the likelihood levels of their occurrence and possible category of the consequences which, after thorough evaluation, will shape the decision making. This type of analysis was applied to Mosul Dam as a case study and resulted in definite recommendations.
基金supported by the National Natural Science Foundation of China (Grant No. 50779009)
文摘It is of great importance to establish the dam failure risk criteria for dam risk assessment and management. Presently, the F-N curve method is widely applied in practice, in which the F-N curves are used for establishing the criteria for separate risks caused by the dam failure in life, economy, environment, and society respectively. In this paper, in consideration of the overlying effect by two or more types of risk losses resulting from the dam failure at the same time, the F-N curved surface method is presented for establishing the integrated dam failure risk criteria. In this method, the named F-N curved surfaces are established, and by these curved surfaces, the acceptable, the allowable, and the unallowable integrated risk zones can be defined.
基金supported by the National Key Basic Research Program of China(Grant No.2013CB036403)
文摘This paper discusses the methods of establishing risk criteria for dams and reviews the application of dam risk criteria for individuals and societies in different countries or districts. Given the conditions in China and considering the public safety and acceptance of dam risk, historical dam break data and current design standards, individual and societal risk criteria for dams are proposed. The tolerable dam risk criteria for individuals should be set to 10-5-10-7 per annum based on project scale, for ex- ample, approximately 1.0xl0 7 per annum, which corresponds to a reliability index of 4.2 based on a 100-year lifespan for a first-class or large project. The societal limit for risk tolerance for dams should be set to approximately 10-3-10-5 per annum, corresponding to the fatality range from 1 to 100 and be horizontally extended to 1000, and F-N curves are proposed. It was also found that the reliability indices of Chinese Standard （GB 50199-2013） and Eurocodel （2002） are different, but they have the same level of safety measured by the annual probability of failure. The research results have significance for establishing dam risk criteria.
基金supported by the Innovative Research Groups of the National Natural Science Foundation of China(Grant No.51321065)the National Basic Research Program of China("973"Project)(Grant No.2013CB035906)the National Natural Science Foundation of China(Grant No.51339003)
文摘The applied technology of high roller-compacted concrete(RCC) dams is quite complicated because of various risk factors, including the weather condition, supply of concrete aggregate, efficiency of transport machinery and dam surface machinery, and so on. In order to ensure the comprehensiveness, accuracy and objectivity of construction schedule risk analysis, a mathematical model called improved correlated schedule risk analysis model(CSRAM) is proposed in this paper. This model takes into account not only the construction features of high RCC dams, but also the stochastic variations of risk factors with the construction schedule, as well as their comprehensive effects. Using Monte Carlo method to solve this model enables the completion probability of a high RCC dam construction within plan time, and uncertainty analysis of risk factors. Compared with the conventional CSRAM, the improved CSRAM has higher completion probability and more convergent distribution of a simulation period, making analysis results more accurate and closer to actual engineering conditions. Among the ten risk factors selected, efficiency of dam surface machinery and proficiency of workers are found to be of the maximum uncertainty.
