ABSTRACT
In this paper, the main risk groups which are specific to projects related to underground works, such as: difficult or unclear geotechnical and environmental conditions and constraints; proper selection of design, construction and monitoring methods and tunnelling equipment; safety hazards in working confined underground environment; onerous contractual conditions and unbalanced risk allocation, were discussed. This research presents the results of a study of the types, causes, and frequency of claims in a variety of underground projects (metro lines, road tunnels and utility tunnels) which were constructed in densely populated urban area in soft ground using different tunnelling methods in Tehran, Iran. The data were analyzed and the results of this analysis along with recommendations on how to reduce/prevent claims in tunnelling projects are then presented.
