The application of reliability-based methods for design of structures has been researched for several decades. Lately, the progress towards practical application of such methods has been strong, in particular for geotechnical structures in soil. One reason is likely that the Eurocodes allow reliability-based methods to verify limit states. As there currently is an ongoing discussion on whether the Eurocodes also should cover underground excavation in
rock, there is now reason to study whether reliability-based methods are applicable also for
structures in rock.
This research project has analysed for which types of design situations in underground excavation in rock that reliability-based design methods are suitable. The applicability of the semi-probabilistic method of partial factors was also studied. Based on the analysis, this report lists a number of research questions that need further attention before reliabilitybased methods can be applied fully to underground excavation in rock.
The research was carried out as a senior research project at the Division of Soil and Rock Mechanics at KTH Royal Institute of Technology. The research project is part of the Swedish research collaboration TRUST (www.trust-geoinfra.se). The project was funded by the Development Fund of the Swedish Construction Industry (SBUF), the Swedish Hydropower Centre (SVC), the Rock Engineering Research Foundation (BeFo), and the
Swedish Nuclear Waste Management Co (SKB).
A group of experts has been involved in the project and provided valuable comments on our work: Håkan Stille, KTH; Mats Holmberg, Tunnel Engineering; Björn Stille, Sweco.
The support of our reference group is also grateful acknowledged. The reference group consisted of Per Tengborg, BeFo; Mats Holmberg, Tunnel Engineering; Robert Sturk, Skanska; Tommy Ellison, Besab; Jonny Sjöberg, Itasca/LTU; Håkan Stille, KTH; Stefan Larsson, KTH; Isabelle Olofsson, SKB; Lars Olof Dahlström, Chalmers/NCC; and Cristian Andersson, SVC.
Stockholm in September 2016
Per Tengborg