Developing a cloud model based risk assessment methodology for tunnel-induced damage to existing pipelines

This paper presents a cloud model (CM) based approach with step-by-step procedures for risk assessment of existing pipelines in tunneling environments (RAEPTE), where CM provides a basis for uncertainty transforming between qualitative concepts and their quantitative expressions. An evaluation index system of multiple layers and attributes is established for RAEPTE based upon the tunnel-induced pipeline failure mechanism analysis. The evaluation result is assessed by the correlation with CMs of each risk level. A confidence indicator is proposed to illustrate the reliability of evaluating results. Risk analysis for ten underground buried pipelines adjacent to the construction of Wuhan Metro Line Two in China is shown in a case study. Comparisons between different evaluation methods are further discussed according to results. The proposed approach is verified to be a more competitive solution, where the uncertainties of fuzziness and randomness are incorporated in the risk assessment system. This approach can serve as a decision tool for the safety risk assessment in other similar projects, and to increase the likelihood of a successful project in an uncertain environment.