Rockfall barrier in reinforced soil, S.P. 56

Edilgrid® for the rockfall barrier, S.P. 56

Edilgrid®: woven polyester geogrids with PVC coating for the construction of rockfall barriers.

Problem

Along the S.P. 56 road in Caoria, between the villages of Caoria and Canal San Bovo, several landslide and rockfall events occurred on the roadway over the years. Rocks fell onto the road on multiple occasions. This required the planning and design of a series of works to guarantee the safety of drivers.

To avoid these dangerous situations, engineers initially considered building a 1,700 m tunnel. The tunnel would have been built just uphill from the village of Canal San Bovo. However, this solution was judged unsuitable, since it only partially resolved the problem, addressing just the first section of the road.

The option considered most convenient and effective was to secure the current road alignment using different techniques, depending on the specific conditions found. Specifically, from km 1+570 to km 2+320, over a stretch of 850 m, engineers planned an uphill rockfall barrier made of reinforced soil. This involved shifting the roadway downhill and building a rock revetment along the Vano stream, to control erosion at the foot of the slope. In addition, a system was planned for draining and disposing of rainwater from the slope above.

Solution

To build a rockfall barrier able to secure the road section from both falling rocks and avalanches, engineers chose a specific approach. The technology selected was vegetated reinforced soil.

Beyond the usual internal, composite, external and global stability checks, engineers carried out analyses of the uphill slope. These analyses helped determine the trajectory and size of the design rockfall block, as well as its impact energy.

Following these investigations, engineers designed a barrier with a 60° slope on the uphill side and 70° on the downhill side. Its dimensions are: 5.00 m in height, 3.00 m wide at the top and 5.00 m at the base. The structure is built with woven polyester Edilgrid® geogrids, PVC coated, spaced 50 cm apart.

After a short time, the face of the barrier became fully vegetated, blending perfectly into the surrounding environment.