Slope protection design Brseč – Mošćenička Draga
For many years, drivers on the DC66 state road from Opatija to Mošćenička Draga had to be very cautious because of occasional rockfalls along the edge of the road. To prevent further rockfalls, Hrvatske ceste d.o.o. invested in the remediation of the unstable slopes in 2019.
For the main and detailed slope protection design, we have carried out engineering geological and geotechnical exploration and investigation works. These works consisted of engineering geological mapping, geological prospecting of the wider area, geotechnical prospecting of the location and previous research data processing.
As part of the slope protection, specific types of protection measures have been determined with regard to the position. The remediation included the installation of a protective mesh, steel ropes, rod and self-drilling anchors, the underpinning of unstable parts of the slope, the removal of unstable blocks, slope protection with shotcrete and the installation of a barrier for protection against debris.
A protective galvanized double-twisted hexagonal wire mesh Type 8×10, additionally reinforced with a steel rope of Ø 12.0 mm, was placed on parts of the slope to prevent the rock blocks from falling. In addition, rod anchors with a diameter of 32 mm and length L = 3.0 and 6.0 m and rod anchors with a diameter of 40 mm and length L = 9.0 and 12.0 m were installed. The anchors were installed in a general grid of 2.5 x 2.5 m and 3.0 x 3.0 m.
Reinforced mesh Q-188, two layers of shotcrete 5.0 cm thick and self-drilling rod anchors with a diameter of 32 mm and a length of L = 3.0 m were installed on the parts of the slopes protected using shotcrete. The anchors were installed in a general grid of 2.5 x 2,5 m.
A barrier for protection against debris was constructed on certain parts of the slope, in order to protect against the falling of smaller unstable blocks from the top of the slope. A barrier of H = 1.85 m height and L = 35.0 m length was constructed.
Engineering supervision of remediation works was carried out, which included the analysis and verification of the situation on the field.