1. ROCK FALL HAZARDS Part 12

2. Rockfalls Rockfalls are a common problem along highways in mountainous terrainRockfalls are a common problem along highways in mountainous terrain They can be costly and deadly; easily triggered by short bursts of intense precipitationThey can be costly and deadly; easily triggered by short bursts of intense precipitation

3. Many rock masses are mixtures of dissimilar materials with markedly contrasting stiffness, as seen in this glacial tillMany rock masses are mixtures of dissimilar materials with markedly contrasting stiffness, as seen in this glacial till

4. Rock Falls 70% of all rockfalls occur during the initial fall freeze or initial spring thaws Rock falls are generally driven by pore pressures, not by the volume of water. Its all about pressure, not volume.

5. Standard guidelines exist for mitigating damage from rockfallsStandard guidelines exist for mitigating damage from rockfalls These include debris ditches, rock fences, and placing mesh on the raveling slope using rockboltsThese include debris ditches, rock fences, and placing mesh on the raveling slope using rockbolts Rockfall Mitigation

6. Triple twisted galvanized or PVC coated gabion wire mesh is an excellent structural material to employ on raveling rock slopes where insufficient right-of-way exists to construct a catchment ditch and fence.  Triple twisted galvanized or PVC coated gabion wire mesh is an excellent structural material to employ on raveling rock slopes where insufficient right-of-way exists to construct a catchment ditch and fence.  Some mechanism for periodic mucking of accumulated debris should be incorporated into the remedial scheme  Most rockfalls occur during first significant freeze or thaw cycles

7. Design details for typical rockbolt stabilization scheme on raveling rock cut slope (from Rogers, 2003)