THE OVERVIEW AND STUDY ON THE MODELING OF RISK ACCEPTANCE CRITERIA FOR TUNNEL AND UNDERGROUND ENGINE...
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THE OVERVIEW AND STUDY ON THE MODELING OF RISK ACCEPTANCE CRITERIA FOR TUNNEL AND UNDERGROUND ENGINEERING. Hu Qunfang Department of Geotechnical Engineering Tongji University 2005-8-27. Contents. Introduction The model of risk acceptance criterion

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Hu Qunfang Department of Geotechnical Engineering Tongji University 2005-8-27

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Hu qunfang department of geotechnical engineering tongji university 2005 8 27

THE OVERVIEW AND STUDY ON THE MODELING OF RISK ACCEPTANCE CRITERIA FOR TUNNEL AND UNDERGROUND ENGINEERING

Hu Qunfang

Department of Geotechnical Engineering Tongji University

2005-8-27


Contents

Contents

  • Introduction

  • The model of risk acceptance criterion

  • The classification of risk acceptance criteria

    • Individual Risk

    • Social Risk

    • Economic Risk

    • Environmental Risk

  • Discussion and Conclusion


  • Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    Introduction

    Some Uncertainties within the Tunnel and Underground Projects

    • the inherent uncertainties and adverse unexpected conditions, including ground and groundwater and their variability, the complicated surrounding of construction site, etc.

    • much engineering investment, long construction time and long service life.

    • the complexity and immaturity of applied technology.

    • the incompetence of decision-making, management and organization.

    • human factors and /or human errors.


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    Risk Acceptance Criteria

    Collection of Information

    Risk Management and Control

    Tunnel and

    Underground Projects

    Introduction

    Risk Decisions

    WORLD

    Risk System Boundary

    The process of risk decision-making


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The purpose of risk management

    Introduction

    Risk Management

    • Risk identification

    • 风险辨识

    • Risk Assessment

    • 风险估计

    • Risk Analysis

    • 风险分析

    • Risk Decision-making

    • 风险决策

    • Risk Control

    • 风险控制

    The mode of risk management and control


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    Introduction

    Therefore, in order to decrease and mitigate all these risks in tunneling and underground projects, we should pay much attention to the risk management and control during the different stages of the entire projects life from the theory to start of operation. And some risk acceptance criteria for decision-making should be established qualitatively or quantitatively in advance.


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The model of risk acceptance criterion

    The development and implementation of risk acceptance criteria involves :

    • Perception of risk: ensure that levels of system risk, such as safety, economy and environment, is acceptance (or tolerable).

    • Formal decision analysis: analytical techniques to balance or compare risks against benefit (e.g. risk cost-benefit analysis, life-cycle cost analysis) .

    • Regulatory safety goals: legislative and statutory framework for the development and enforcement of risk acceptance criteria.


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The model of risk acceptance criterion

    Some countries and organizations have established and adopted some risk acceptance criterion, such as the U.S Nuclear Regulatory Commission (NRC), U.K Health and Safety Executive (HSE), Dutch Technical Advisory Committee on Water Defenses (TWA) and other regulatory authorities, etc. Mainly, there are two basic principles for defining the risk level used for a qualitative or quantitative risk analysis.

    • As Low As Reasonably Possible (ALARP)

    • As Low As Reasonably Achievable (ALARA)

    The definition foe such terms as ‘Low’, ‘Reasonably’, ‘Possible’ and ‘Attainable’ are highly subjective and prone to being interpreted in a conservative manner. Some expressions and models have been made to define these criteria in more tangible limit in terms of quantitative risks.


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The model of risk acceptance criterion


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The classification of risk acceptance criteria

    The risk acceptance criteria can be classified into fourelementary categories from the recent overview of recent research around the world (Li Dianqing et al, 2003, S. N. Jonkman et al, 2003) .

    • Individual Risk

    • Social Risk

    • Economical Risk

    • Environmental Risk


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The classification of risk acceptance criteria

    (1)Individual Risk

    The individual risk (IR), as used by the Dutch Ministry of Housing, Spatial Planning and Environment (VROM), is defined as the probability that an average unprotected person, permanently present at a certain location, is killed due to an accident resulting from a hazardous activity.

    To limit the risks, there are many criteria such as ALARA, Risk Matrix, AFR (Annual Fatality Risk), AIR (Average Individual Risk) and AI (Aggregated Indicator) etc.


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The classification of risk acceptance criteria

    (1)Individual Risk

    ALARP


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The classification of risk acceptance criteria

    (1)Individual Risk

    Risk Matrix


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    • VROM:

    • TWA:

    Public:

    Workers:

    The classification of risk acceptance criteria

    (1)Individual Risk

    • Bohnenblust:

    • HSE:


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The classification of risk acceptance criteria

    (1)Individual Risk

    Besides the individual risk as mentioned above, four other expressions are described (T. Bedford et al, 2001).

    • The Loss of Life Expectancy

    • Social Risk The Delta Yearly Probability of Death

    • The Activity Specific Hourly Mortality Rate

    • A variant is the Death per Unit Activity


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The classification of risk acceptance criteria

    (2)Social Risk

    The societal risk is defined as “the relationship between frequency and the number of people suffering from a specified level of harm in a given population from the realization of specified hazards” (Institute of Chemical Engineering, 1985) .

    To limit the social risks, there are many criteria such as ALARP, Risk Matrix, F-N curve, PLL (Potential Loss of Life), FAR (Fatal Accident Rate), VIIH (Value of Injuries and Ill Health), ICAF (Implied Cost of Averting a Facility) and LQI (Life Quality Index) etc.


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    The classification of risk acceptance criteria

    (2)Social Risk

    The societal risk is often represented graphically in an F-N curve which is first used by Farmer F.R. (Farmer FR, 1967) and originally introduced for the assessment of the risks in the nuclear industry (H.W. Kendall et al, 1977) .

    PLL(the potential loss of life):


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    (fatalities/year)

    (fatalities/year)

    The classification of risk acceptance criteria

    (2)Social Risk

    Some international standards limiting the FN-curve


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    (US $/per year)

    The classification of risk acceptance criteria

    (3)Economic Risk

    Besides the loss of life due to certain activities, the economic risks play an important role in risk analysis. A FD-curve displays the probability of exceedance as a function of the economic damage (S. N. Jonkman et al, 2003). The FD-curve and the expected value of the economic damage can be derived from the PDF of the economic damage.


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    Highly potential ER:

    Lowly potential ER:

    The classification of risk acceptance criteria

    (4)Environmental Risk

    The competitive standing of the Norwegian offshore sector (NORSOK) has proposed the probability of exceedance of the time needed by the ecosystem to recover from the damage as a measure for environmental risk (NORSOK, 1998).


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    Discussion and Conclusion

    • The unitive model of risk occurrence mechanism in tunnel and underground engineering is showed as follow:

    How can we get the parameter values of C and n?


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    Discussion and Conclusion

    The model of risk occurrence mechanism of

    tunnel and underground engineering


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    Discussion and Conclusion

    • In order to establish the unitive model of risk acceptance criteria in detail, we should design a database, which is used for storing some risk events investigation and record data, and do some research work based on the existing risk acceptance criteria (Beacher GB et al,1987) all over the world.

    Some Empirical Rates of Failure for Civil Engineering

    By Robert V. Whitman and Greg Baecher


    Hu qunfang department of geotechnical engineering tongji university 2005 8 27

    Discussion and Conclusion

    • Human error is an important source of risk. How to assess the human errors and whether it can be accepted that depend on the context of risk acceptance. But it is a blank research area that needs us to pay attention.

    • Risk analysis is a systematical science which is composed of many main subjects. There are many problems which need to be resolved in future. Fortunately, Our workgroup has a good beginning and promotes the further research by our teachers.


    Thanks for your attention

    Thanks for Your Attention !

    to Shanghai and Tongji!


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