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1.
In this paper, the potential risk of undesirable events occurring during tunneling with application of a shield tunnel boring machine (TBM) method is discussed along with the risk analysis which can systematically assess overall risk levels. Potential risks and typical scenarios pertaining to shield TBM tunnels have been investigated based on previous case histories and correspondence with experts. The relevant risks from undesirable events were categorized into four groups: cutter-related malfunction, machine blockage or hold-up, mucking problems that hinder transporting excavated materials, and segment defects. A fault-tree set was constructed by grouping risk factors (or causes) into geological, design and construction/management factors. Risk analysis was performed by adopting fault-tree analysis (FTA) and an analytic hierarchy process (AHP) with consideration of the probability and impact of the risks. In addition, the proposed method was reliably validated by comparison with field observation, and thus indicates its applicability to risk management for shield TBM tunneling.  相似文献   
2.
根据工程具体情况采用WBS方法按工序进行分解,然后采用故障树法对风险进行分析、识别,建立风险清单。在此基础上,采用模糊综合评判模型进行风险评估,得出基坑施工风险等级,为后来的风险应对提供参考依据。  相似文献   
3.
论述了所设计的计算机辅助可视化故障树分析系统的功能及程序结构与设计原理。系统由编辑生成、分析计算、诊断输出3个模块组成,使得故障树的生成与分析非常直观而简便,只需用鼠标在屏幕上绘制出故障树图,系统就能自动识别并进行定性与定量分析。  相似文献   
4.
Natural gas, one of the cleanest, most efficient and useful of all energy sources, is a vital component of the world’s supply of energy. To make natural gas more convenient for storage and transportation, it is refined and condensed into a liquid called liquefied natural gas (LNG). In a LNG site, safety is a long-team and critical issue. The emergency shutdown (ESD) system in the LNG receiving terminal is used to automatically stop the pumps and isolate the leakage section. Fault-tree analysis (FTA) has been widely used for providing logical functional relationships among subsystems and components of a system and identifying the root causes of the undesired failures in a system. In the conventional FTA for the ESD system, we usually assume that exact failure probabilities of events are collected. However, in most real applications, first, the FTA for the ESD system needs to be made at a early design or manufacturing stage, certain new components normally used without failure data; secondly, sometimes the environmental change in the system during the operation periods. This makes more difficult to gather past exact failures data for the FTA. To complete the FTA of the ESD system under these uncertain situations, we apply the intuitionistic fuzzy sets (IFS) theory to the FTA. We generate the intuitionistic fuzzy fault-tree interval, and the intuitionistic fuzzy reliability interval for the ESD system. We also present an algorithm to find the critical components in the system based on IFS–FTA and determine weak paths in the ESD system, where the key improvement must be made.  相似文献   
5.
This paper shows how heterogeneous stochastic modelling techniques of increasing modelling power can be applied to assess the safety of a digital control system. First, a Fault-Tree (FT) has been built to model the system, assuming two-state components and independent failures. Then, the FT is automatically converted into a Bayesian Network, allowing to include more modelling details and localized dependencies. Finally, in order to accommodate repair activities and perform an availability analysis, the FT is converted into a Stochastic Petri Net (SPN). Moving from a combinatorial model (the FT) to a state space based model (the SPN) increases the modelling flexibility, but incurs into the state space explosion problem. In order to alleviate the state space explosion problem, this paper resorts to the use of a particular type of high level (coloured) Petri nets called SWN. A digital control system is considered as a case study, and safety measures have been evaluated, referring to the emergent standard IEC 61508.  相似文献   
6.
针对传统故障树生成与诊断方法过于复杂的问题,提出了一套适合工程实践用的故障树生成及诊断模型.利用虚拟仪器技术研制了可视化的故障树自动生成与诊断软件,并利用该软件程序自动调用相应的虚拟仪器完成对该检测点的测试和诊断.实际应用表明,该方法满足设计要求,可无缝移植到其他数字化仪器设备的故障诊断过程中.  相似文献   
7.
近年来换流阀冷却系统频繁故障导致直流系统单双极闭锁,其可靠性对跨区电网的稳定运行影响非常大,然而相关文献对高压直流输电系统进行可靠性评估时,凡涉及到阀冷却系统均以故障忽略不计为参数假设进行研究,与工程实际情况有一定的偏差。文中结合了故障树(FTA)法,根据系统抽样样本的统计特征来获得系统的可靠性参数,建立了换流阀冷却系统可靠性模型,为决策者提供基础数据支撑。  相似文献   
8.
The development of a systematic fault-tree synthesis procedure for the override control systems is presented in this paper. The unique configuration of the digraph model under study is first described and then analyzed in detail. On the basis of qualitative simulation of the fault propagation patterns, the corresponding generalized fault-tree structures are then established. It can be observed clearly from the simulation results that none of the existing techniques are capable of producing the correct fault-trees. To demonstrate the correctness of our analysis, successful application of the proposed structure to furnace operation is also presented.  相似文献   
9.
A procedure for the failure cause identification of tribo-mechanical systems is presented based on fault-tree using a digraph approach. A variable-event system digraph for a tribo-mechanical system is suggested which takes into account structure of the system. A top event or undesirable event for the system is then defined and the fault-tree for this top event is deduced from the digraph by back-tracking it. The analysis of the fault-tree aids the design and practising engineers in design and development of reliable, safe and productive tribo-mechanical systems. The methodology is applied to journal bearing oil supply system in a power plant application.  相似文献   
10.
文章用故障树分析方法对秦山核电厂高压安注系统的可靠性进行了分析。这项工作是采用西德反应堆安全研究所(GRS)研制的RALLY程序包进行的,内容包括系统不可用度计算、不确定度分析、统计评估以及重要度分析。有关分析结果为寻找秦山厂高压安注系统的薄弱环节、改进系统设计提供了参考依据。  相似文献   
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