ABSTRACT
Tunneling-induced ground movements are counted as a major factor guiding the design of tunnels in urbanized areas. Due to high level of third-party exposure associated with their construction, at least a simplified risk management approach should be used from the early stages of the project, to ensure its success and to protect interests of various stakeholders. Depending on expected accuracy of prediction at a given stage, qualitative as well as quantitative risk assessment methods can be used. Generally, they all involve the assessment of predicted extent of the influence zone, magnitude of expected ground deformation, and definition of limiting criteria for specific structures. Furthermore, the predicted impact is traditionally assessed in a limit state design framework, by simple comparison of predicted deformations with their assumed limiting values. However, to accommodate more risk oriented attitude, it can be extended to performance based design, where prediction is related to expected risk levels as well as potential consequences of failure for each structure. The paper presents the preliminary proposal of qualitative risk assessment approach and guidance that may be applied specifically for the purpose of assessing impact of tunneling-induced ground deformations on adjacent structures.
