Several potential failure modes generally exist in rock slopes because of the existence of massive structural planes in rock masses. A system reliability analyses method for rock slopes with multiple failure modes bas...Several potential failure modes generally exist in rock slopes because of the existence of massive structural planes in rock masses. A system reliability analyses method for rock slopes with multiple failure modes based on nonlinear Barton-Bandis failure criterion is proposed. The factors of safety associated with the sliding and overturning failure modes are derived, respectively. The validity of this method is verified through a planar rock slope with an inclined slope top and tension crack. Several sensitivity analyses are adopted to study the influences of structural-plane parameters, geometric parameters, anchoring parameters and fracture morphology on the rock slopes system reliability.展开更多
风险评估技术对保障长输管道的安全运行具有重要作用,场站管道由于结构的复杂及与设备联系密切,对它进行风险评估尤为关键。通过对所研究的场站管道评估数据的分析,依据国内的相关标准和国外DNV软件,研究开发了针对场站管道的RBI(Risk B...风险评估技术对保障长输管道的安全运行具有重要作用,场站管道由于结构的复杂及与设备联系密切,对它进行风险评估尤为关键。通过对所研究的场站管道评估数据的分析,依据国内的相关标准和国外DNV软件,研究开发了针对场站管道的RBI(Risk Based Inspection)评估系统。主要研究内容包括:研究确定了场站管道RBI评估方法;建立场站管道基于检测的风险评估模型,采用Labview和Matlab软件开发了场站管道的RBI评估系统软件;利用此软件可进行场站管道的失效可能性和失效后果两方面的分析,并综合得到场站管道的风险评估结论,由此可有针对性地提出提高场站管道安全可靠性的措施。通过对白沙湾输油站管道的风险评估实例验证了所开发的系统的可行性和正确性。展开更多
Quantitative safety assessment of safety systems plays an important role in decision making at all stages of system lifecycle, i.e., design, deployment and phase out. Most safety assessment methods consider only syste...Quantitative safety assessment of safety systems plays an important role in decision making at all stages of system lifecycle, i.e., design, deployment and phase out. Most safety assessment methods consider only system parameters, such as configuration, hazard rate, coverage, repair rate, etc. along with periodic proof-tests （or inspection）. Not considering demand rate will give a pessimistic safety estimate for an application with low demand rate such as nuclear power plants, chemical plants, etc. In this paper, a basic model of IEC 61508 is used. The basic model is extended to incorporate process demand and behavior of electronic- and/or computer-based system following diagnosis or proof-test. A new safety index, probability of failure on actual demand （PFAD） based on extended model and demand rate is proposed. Periodic proof-test makes the model semi-Markovian, so a piece-wise continuous time Markov chain （CTMC） based method is used to derive mean state probabilities of elementary or aggregated state. Method to determine probability of failure on demand （PFD） （IEC 61508） and PFAD based on these state probabilities are described. In example, safety indices of PFD and PFAD are compared.展开更多
The stiffened cylindrical shell is commonly used for the pressure hull of submersibles and the legs of offshore platforms. There are various failure modes because of uncertainty with the structural size and material p...The stiffened cylindrical shell is commonly used for the pressure hull of submersibles and the legs of offshore platforms. There are various failure modes because of uncertainty with the structural size and material properties, uncertainty of the calculation model and machining errors. Correlations among failure modes must be considered with the structural reliability of stiffened cylindrical shells. However, the traditional method cannot consider the correlations effectively. The aim of this study is to present a method of reliability analysis for stiffened cylindrical shells which considers the correlations among failure modes. Firstly, the joint failure probability calculation formula of two related failure modes is derived through use of the 2D joint probability density function. Secondly, the full probability formula of the tandem structural system is given with consideration to the correlations among failure modes. At last, the accuracy of the system reliability calculation is verified through use of the Monte Carlo simulation. Result of the analysis shows the failure probability of stiffened cylindrical shells can be gained through adding the failure probability of each mode.展开更多
基金Project(51978666) supported by the National Natural Science Foundation of ChinaProject(2018-123-040) supported by the Guizhou Provincial Department of Transportation Foundation, ChinaProject(2019zzts009) supported by the Fundamental Research Funds for the Central Universities, China。
文摘Several potential failure modes generally exist in rock slopes because of the existence of massive structural planes in rock masses. A system reliability analyses method for rock slopes with multiple failure modes based on nonlinear Barton-Bandis failure criterion is proposed. The factors of safety associated with the sliding and overturning failure modes are derived, respectively. The validity of this method is verified through a planar rock slope with an inclined slope top and tension crack. Several sensitivity analyses are adopted to study the influences of structural-plane parameters, geometric parameters, anchoring parameters and fracture morphology on the rock slopes system reliability.
文摘风险评估技术对保障长输管道的安全运行具有重要作用,场站管道由于结构的复杂及与设备联系密切,对它进行风险评估尤为关键。通过对所研究的场站管道评估数据的分析,依据国内的相关标准和国外DNV软件,研究开发了针对场站管道的RBI(Risk Based Inspection)评估系统。主要研究内容包括:研究确定了场站管道RBI评估方法;建立场站管道基于检测的风险评估模型,采用Labview和Matlab软件开发了场站管道的RBI评估系统软件;利用此软件可进行场站管道的失效可能性和失效后果两方面的分析,并综合得到场站管道的风险评估结论,由此可有针对性地提出提高场站管道安全可靠性的措施。通过对白沙湾输油站管道的风险评估实例验证了所开发的系统的可行性和正确性。
文摘Quantitative safety assessment of safety systems plays an important role in decision making at all stages of system lifecycle, i.e., design, deployment and phase out. Most safety assessment methods consider only system parameters, such as configuration, hazard rate, coverage, repair rate, etc. along with periodic proof-tests （or inspection）. Not considering demand rate will give a pessimistic safety estimate for an application with low demand rate such as nuclear power plants, chemical plants, etc. In this paper, a basic model of IEC 61508 is used. The basic model is extended to incorporate process demand and behavior of electronic- and/or computer-based system following diagnosis or proof-test. A new safety index, probability of failure on actual demand （PFAD） based on extended model and demand rate is proposed. Periodic proof-test makes the model semi-Markovian, so a piece-wise continuous time Markov chain （CTMC） based method is used to derive mean state probabilities of elementary or aggregated state. Method to determine probability of failure on demand （PFD） （IEC 61508） and PFAD based on these state probabilities are described. In example, safety indices of PFD and PFAD are compared.
基金The Defence Advance Research Program of Science and Technology of Ship Industry(Grant No.11J1.3.1)
文摘The stiffened cylindrical shell is commonly used for the pressure hull of submersibles and the legs of offshore platforms. There are various failure modes because of uncertainty with the structural size and material properties, uncertainty of the calculation model and machining errors. Correlations among failure modes must be considered with the structural reliability of stiffened cylindrical shells. However, the traditional method cannot consider the correlations effectively. The aim of this study is to present a method of reliability analysis for stiffened cylindrical shells which considers the correlations among failure modes. Firstly, the joint failure probability calculation formula of two related failure modes is derived through use of the 2D joint probability density function. Secondly, the full probability formula of the tandem structural system is given with consideration to the correlations among failure modes. At last, the accuracy of the system reliability calculation is verified through use of the Monte Carlo simulation. Result of the analysis shows the failure probability of stiffened cylindrical shells can be gained through adding the failure probability of each mode.
