Developing a risk assessment method for complex pipe jacking construction projects

Pipe jacking (PJ) construction is a highly complex and uncertain process so that performing an accurate risk assessment is essential to the success of a project. This study presents an innovative risk assessment model which combines fuzzy inference with failure mode and effect analysis (FMEA) to improve the effectiveness of existing risk assessment methods for pipe jacking construction. The proposed model maps the relationship between occurrence (O), severity(S), and detection (D) with the level of criticality of risk events in three steps: fuzzification, fuzzy rule-based inference, and defuzzification. A case study of a PJ construction project for water transmission in Shanghai, China is presented to demonstrate and validate the proposed method. A total of 31 potential risks was identified according to the PJ construction procedure and two-round Delphi questionnaire surveys. By using the proposed fuzzy-FMEA approach, the most critical risks in the PJ construction process can be identified, in particular, the shaft structure construction, jacking operation, and steel pipe segments welding. The proposed method overcomes the inherent weaknesses of traditional FMEA method and provides a reliable and distinguishable risk ranking system by properly reflecting the complexity of PJ construction environment. The study also provides a comprehensive risk identification and evaluation tool for industrial practitioners who manage or involve with PJ construction projects.     

基于模糊理论大跨浅埋公路隧道施工风险评估

鉴于大跨浅埋公路隧道施工风险评估的模糊属性,采用模糊数学方法定量化处理施工风险估计中的定性问题。建立了茅山隧道施工风险多层次模糊综合评价数学模型,运用模糊理论对专家给出的茅山隧道施工各项风险因素的概率等级和损失等级隶属度进行统计分析,得到了各因素的概率及损失估计结果。基于R=P×C模型考虑了风险因素发生概率及损失对风险评估的影响,得到各风险因素、基本风险事件的风险等级,确定茅山隧道施工的安全风险、环境影响风险及整体风险等级为四级,应采取有效的风险控制措施应对。研究表明,模糊理论解决了风险评估中的模糊性及量化问题,可作为评估大跨浅埋公路隧道施工阶段风险的有效模型。     

基于模糊层次分析法的瓦斯隧道施工风险评价

瓦斯隧道在施工过程中面临众多复杂的风险,而且施工风险源具有复杂性、随机性和模糊性,目前的研究方法难以对其进行准确定量分析。笔者结合实际工程的施工,通过深入分析影响瓦斯隧道施工的风险因素,建立了施工风险评价指标体系,采用专家调查法和层次分析法确定了各级因素的权重,分析得出影响施工的主要、次方面,并运用模糊数学的方法,建立模糊评判模型,对瓦斯隧道施工风险评价指标体系中的单因素和整体进行评价,最终根据评价结果确定了瓦斯隧道的施工风险等级。通过对计算结果分析,该方法在瓦斯隧道的施工风险评价上具有适用性和可靠性。     

A fuzzy approach to construction project risk assessment

The increasing complexity and dynamism of construction projects have imposed substantial uncertainties and subjectivities in the risk analysis process. Most of the real-world risk analysis problems contain a mixture of quantitative and qualitative data; therefore quantitative risk assessment techniques are inadequate for prioritizing risks. This article presents a risk assessment methodology based on the Fuzzy Sets Theory, which is an effective tool to deal with subjective judgement, and on the Analytic Hierarchy Process (AHP), which is used to structure a large number of risks. The proposed methodology incorporates knowledge and experience acquired from many experts, since they carry out the risks identification and their structuring, and also the subjective judgements of the parameters which are considered to assess the overall risk factor: risk impact, risk probability and risk discrimination. All of these factors are expressed by qualitative scales which are defined by trapezoidal fuzzy numbers to capture the vagueness in the linguistic variables. The most notable differences with other fuzzy risk assessment methods are the use of an algorithm to handle the inconsistencies in the fuzzy preference relation when pair-wise comparison judgements are necessary, and the use of trapezoidal fuzzy numbers until the defuzzification step. An illustrative example on risk assessment of a rehabilitation project of a building is used to demonstrate the proposed methodology.     

Risk analysis in ultra deep scientific drilling project — A fuzzy synthetic evaluation approach

Exploration of deep earth requires ultra deep drilling attempts on the sea or continent, which is the main goal of scientific drilling projects currently established. Uncertain geological complexity, high requirement for R&D of critical equipment as well as high demand of practical performance has to be encountered during a scientific drilling project, making it full of challenge and risks. Risk management, therefore, is critically proposed for scientific drilling projects in order to reduce the risks. However, many traditional risk assessment methods may not perform well in the project due to lack of high quality data of historical record and sufficient information. This paper, therefore, proposes a fuzzy synthetic evaluation approach for scientific drilling project risk assessment. Four criteria — probability, severity, non-detectability and worsening factor are utilized to evaluate individual and overall risks comprehensively. Linguistic terms instead of numerical values are employed to evaluate each risk normally done by experts. AHP/ANP is used to determine sensible weights of each criterion. Values of risk indices are calculated to represent the level of each risk and the overall risk. Finally, a case study on risk analysis of SinoProbe-09 project conducted in Jilin University is tested to demonstrate the procedure of the method and to validate the proposed method. Results show that the risks of the scientific drilling project can be assessed effectively and efficiently.     

建筑工程施工安全风险综合等级评估模型及应用

建筑工程施工安全风险评估是管控建筑安全与质量的重要环节,但当前研究主要关注整体风险,对各指标的风险识别和预防缺乏具体指导意义。通过对影响施工安全的风险因素分析,建立建筑工程施工安全风险评估指标体系;利用有序比值法确定风险指标权重,进而构建基于级别特征值的建筑工程施工安全风险模糊综合等级评估模型。此方法不仅能合理确定整体及各指标风险等级,而且能实现相同等级下的风险大小排序。通过实例分析,表明该模型合理、有效,可为施工单位采取针对性预防措施提供科学决策依据。     

基于 FAHP-BN 的军队工程代建模式风险评估方法

为解决军队工程代建模式风险评估过程中的主观性与不确定性,提出一种模糊层次分析法与贝叶斯网络相结合的风险评估方法。以军队代建工程质量安全事故数据为基础,建立模糊层次分析模型对代建工程风险损失权重进行评估。构建贝叶斯网络,利用 Netica 软件推理风险事件发生概率。结合风险等级隶属函数,得出代建工程整体风险等级。该方法可以有效降低风险评估的主观因素,及时发现高风险节点,更准确地把握风险态势。实例评估结果与工程实际相符,验证了评估方法的合理性和适用性,对工程代建模式风险评估具有一定的参考价值。     

高层住宅太阳能一体化项目风险评价研究

随着城市化进程的加剧,各大城市出现了一大批高层住宅与太阳能热水系统同步设计同步施工的项目,这些项目由于更加的复杂,其风险较传统工程项目的风险有了很大的不同,给项目管理人员的风险管理带来了挑战。为了应对这一挑战,构建了高层住宅太阳能一体化项目风险评价指标体系,并结合了模糊综合评价和层次分析法的优点建立了基于模糊综合评价的风险评价模型,并最终得出了工程项目风险因素发生的概率以及风险因素对于项目目标的影响程度。最后将风险评价模型应用于西安某太阳能示范小区工程中,得出了该项目的风险程度,验证了此模型是可信的,适用的。     

基于模糊层次分析法的代建单位风险评价研究

“代建制”是我国近十年来对政府投资项目传统管理体制改革的产物,具有突出的先进性,能够有效提高政府投资项目的管理水平和投资效益。文章立足于代建单位,分析了代建单位风险评价的意义,利用风险分解结构法对代建单位风险进行了识别,并提出了一种基于层次分析法、Delphi法和模糊数学理论相结合的风险评价方法,建立了代建单位风险因素集和评语集,确定出各因素权重和评判矩阵,构建出模糊评价模型。论文以江苏省某代建项目为例验证了该风险评价方法;评价结果具有参考价值,可以推广使用。     

富水软土长距离非锁口曲线管幕施工风险研究

非锁口曲线管幕工法是为适应复杂地下环境与工程障碍物而发展的隧道非开挖新技术,其施工过程的风险控制是十分值得重视的研究课题,特别是富水软土隧道。本文结合港珠澳大桥拱北隧道暗挖工程,重点研究富水软土长距离非锁口曲线管幕工程施工的风险评估问题。基于富水软土中长距离非锁口曲线管幕施工进行风险分析,得到风险因素对总评指标的权重,再采用专家调查法对单因素进行评价,得到模糊关系矩阵,然后进行合成计算得到综合评判集,建立基于层次分析法的风险模糊评估方法和标准。最后运用该方法对港珠澳大桥拱北隧道管幕工程的施工风险进行分析评估,绘制了风险因素分布直方图,计算得到了综合风险等级,提出了风险控制建议。