Behaviour of the reinforced cuts in flysch rock mass

Abstract

The paper presents some experiences during the reinforced cut construction in the flysch deposits on the Adriatic motorway near city of Rijeka, Croatia. The major part of the motorway was constructed by cutting in flysch rock mass. Stabilities of the cuts were ensured by reinforcing of rock mass with rock bolts and appropriate supporting systems. The self boring rock bolts in combination of multilayered sprayed concrete or reinforced mat construction were used. The shallow boring drains were installed for dissipation of ground water collected at contact of permeable cover and impermeable flysch rock mass. Interactive rock mass cutting design, based on the observational methods, was introduced during the construction. The active design approach has allowed the designer, based on the rock mass conditions and monitoring results, changing the support system at some unfavourable locations. The measured values and the back analysis enabled establishing real rock mass strength parameters and deformability modulus.