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CRITICAL ASSESSMENT OF RMR BASED TUNNEL DESIGN PRACTICES: A PRACTICAL ENGINEER’S APPROACH (2013)
For professional tunnel engineers, for whom money and time are in short supply particularly in early stages of a project, this paper critically assesses what works best with the RMR system, today 40 years after its development and extensive accumulated experience. Five aspects of practical tunnel design are dealt with:
(i) new design charts for rockbolt, shotcrete and steel ribs support as a function of excavation span and rock mass quality,
(ii) deciding on tunnel shape and secondary liners,
(iii) RMR ratings graphs updated for practical applications,
(iv) refining prediction of in situ modulus of deformation based on rock mass quality alone, and
(v) new approach to handling conditions of squeezing ground and rock bursting.
It is demonstrated how numerical modeling of tunnel design issues goes hand-in-hand with RMR-based estimation of rock mass properties and in situ quality.
RAPID EXCAVATION & TUNNELING CONFERENCE, June 2013
Mott MacDonald Limited UK