Abstract
It is well known that encounter of unforeseeable geological condition such as fault and fractured zones or water inrushing in a tunnel construction project leads to substantial cost overrun and delay of construction term. From such a view point, in this paper, a methodology associated with evaluation of cost variation of tunnel construction projects in discontinuous rock mass was presented. The concept of risk, which was ordinary applied to financial engineering, was adopted to the evaluation of cost variation. And the evaluation method such as risk-curve and Value at Risk was adopted. In detail, this paper proposed a method to combine geo-statistics model and discrete fracture network model. In this methodology, geo-statistics model was employed to decide the support pattern, and discrete fracture network model, which was often used for seepage analysis in discontinuous media, was employed to conduct evaluation of discharge along excavated a tunnel. Furthermore, the proposed methodology was applied to evaluate cost variation risk of tunnel excavation by Tunnel Boring Machine, TBM. Finally, results made it clear that the proposed methodology is very useful to clarify dominant risk factors involved in information on in-situ discontinuous rock mass.
