This paper attempts to provide an overview of risk assessment and management practice in underground rock engineering based on a review of the international literature and some personal experience. It is noted that th...This paper attempts to provide an overview of risk assessment and management practice in underground rock engineering based on a review of the international literature and some personal experience. It is noted that the terminologies used in risk assessment and management studies may vary from country to country. Probabilistic risk analysis is probably the most widely-used approach to risk assessment in rock engineering and in geotechnical engineering more broadly. It is concluded that great potential exists to augment the existing probabilistic methods by the use of Bayesian networks and decision analysis techniques to allow reasoning under uncertainty and to update probabilities, material properties and analyses as further data become available throughout the various stages of a project. Examples are given of the use of these methods in underground excavation engineering in China and elsewhere, and opportunities for their further application are identified.展开更多
A simplified fragility analysis of fan type cable stayed bridges usingProbabilistic Risk Analysis (PRA) procedure is presented for determining their failure probabilityunder random ground motion. Seismic input to the ...A simplified fragility analysis of fan type cable stayed bridges usingProbabilistic Risk Analysis (PRA) procedure is presented for determining their failure probabilityunder random ground motion. Seismic input to the bridge support is considered to be a riskconsistent response spectrum which is obtained from a separate analysis. For the response analysis,the bridge deck is modeled as a beam supported on springs at different points. The stiffnesses ofthe springs are determined by a separate 2D static analysis of cable-tower-deck system. The analysisprovides a coupled stiffness matrix for the spring system. A continuum method of analysis usingdynamic stiffness is Used to determine the dynamic properties of the bridges .The response of thebridge deck is obtained by the response spectrum method of analysis as applied to multi-degree offreedom system which duly takes into account the quasi - static component of bridge deck vibration.The fragility analysis includes uncertainties arising due to the variation in ground motion,material property, modeling, method of analysis, ductility factor and damage concentration effect.Probability of failure of the bridge deck is determined by the First Order Second Moment (FOSM)method of reliability. A three span double plane symmetrical fan type cable stayed bridge of totalspan 689 m, is used as an illustrative example. The fragility curves for the bridge deck failure areobtained under a number of parametric variations. Some of the important conclusions of the studyindicate that (ⅰ) not only vertical component but also the horizontal component of ground motionhas considerable effect on the probability of failure; (ⅱ) ground motion with no time lag betweensupport excitations provides a smaller probability of failure as compared to ground motion with verylarge time lag between support excitation; and (ⅲ) probability of failure may considerablyincrease for soft soil condition.展开更多
Integration testing is an integral part of software testing.Prior studies have focused on reducing test cost in integration test order generation.However,there are no studies concerning the testing priorities of criti...Integration testing is an integral part of software testing.Prior studies have focused on reducing test cost in integration test order generation.However,there are no studies concerning the testing priorities of critical classes when generating integration test orders.Such priorities greatly affect testing efficiency.In this study,we propose an effective strategy that considers both test cost and efficiency when generating test orders.According to a series of dynamic execution scenarios,the software is mapped into a multi-layer dynamic execution network(MDEN)model.By analyzing the dynamic structural complexity,an evaluation scheme is proposed to quantify the class testing priority with the defined class risk index.Cost–benefit analysis is used to perform cycle-breaking operations,satisfying two principles:assigning higher priorities to higher-risk classes and minimizing the total complexity of test stubs.We also present a strategy to evaluate the effectiveness of integration test order algorithms by calculating the reduction of software risk during their testing process.Experiment results show that our approach performs better across software of different scales,in comparison with the existing algorithms that aim only to minimize test cost.Finally,we implement a tool,ITOsolution,to help practitioners automatically generate test orders.展开更多
文摘This paper attempts to provide an overview of risk assessment and management practice in underground rock engineering based on a review of the international literature and some personal experience. It is noted that the terminologies used in risk assessment and management studies may vary from country to country. Probabilistic risk analysis is probably the most widely-used approach to risk assessment in rock engineering and in geotechnical engineering more broadly. It is concluded that great potential exists to augment the existing probabilistic methods by the use of Bayesian networks and decision analysis techniques to allow reasoning under uncertainty and to update probabilities, material properties and analyses as further data become available throughout the various stages of a project. Examples are given of the use of these methods in underground excavation engineering in China and elsewhere, and opportunities for their further application are identified.
文摘A simplified fragility analysis of fan type cable stayed bridges usingProbabilistic Risk Analysis (PRA) procedure is presented for determining their failure probabilityunder random ground motion. Seismic input to the bridge support is considered to be a riskconsistent response spectrum which is obtained from a separate analysis. For the response analysis,the bridge deck is modeled as a beam supported on springs at different points. The stiffnesses ofthe springs are determined by a separate 2D static analysis of cable-tower-deck system. The analysisprovides a coupled stiffness matrix for the spring system. A continuum method of analysis usingdynamic stiffness is Used to determine the dynamic properties of the bridges .The response of thebridge deck is obtained by the response spectrum method of analysis as applied to multi-degree offreedom system which duly takes into account the quasi - static component of bridge deck vibration.The fragility analysis includes uncertainties arising due to the variation in ground motion,material property, modeling, method of analysis, ductility factor and damage concentration effect.Probability of failure of the bridge deck is determined by the First Order Second Moment (FOSM)method of reliability. A three span double plane symmetrical fan type cable stayed bridge of totalspan 689 m, is used as an illustrative example. The fragility curves for the bridge deck failure areobtained under a number of parametric variations. Some of the important conclusions of the studyindicate that (ⅰ) not only vertical component but also the horizontal component of ground motionhas considerable effect on the probability of failure; (ⅱ) ground motion with no time lag betweensupport excitations provides a smaller probability of failure as compared to ground motion with verylarge time lag between support excitation; and (ⅲ) probability of failure may considerablyincrease for soft soil condition.
基金Project supported by the National Natural Science Foundation of China(Nos.61902056,61977014,and 61603082)the Shenyang Young and Middle-Aged Talent Support Program,China(No.ZX20200272)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.N2017011)the Open Fund of State Key Lab for Novel Software Technology,Nanjing University,China(No.KFKT2021B01)。
文摘Integration testing is an integral part of software testing.Prior studies have focused on reducing test cost in integration test order generation.However,there are no studies concerning the testing priorities of critical classes when generating integration test orders.Such priorities greatly affect testing efficiency.In this study,we propose an effective strategy that considers both test cost and efficiency when generating test orders.According to a series of dynamic execution scenarios,the software is mapped into a multi-layer dynamic execution network(MDEN)model.By analyzing the dynamic structural complexity,an evaluation scheme is proposed to quantify the class testing priority with the defined class risk index.Cost–benefit analysis is used to perform cycle-breaking operations,satisfying two principles:assigning higher priorities to higher-risk classes and minimizing the total complexity of test stubs.We also present a strategy to evaluate the effectiveness of integration test order algorithms by calculating the reduction of software risk during their testing process.Experiment results show that our approach performs better across software of different scales,in comparison with the existing algorithms that aim only to minimize test cost.Finally,we implement a tool,ITOsolution,to help practitioners automatically generate test orders.
