Components, systems and materials › Slope protection and rockfall › Rockfall embankment
Rockfall embankment
What it is
A rockfall embankment is a large earth or reinforced-soil bund built across the path of falling rocks to stop high-energy blocks that would overwhelm a net barrier.
Where it is used
Below steep rock faces above roads, railways and settlements where expected block energies are very high or repeated impacts are likely.
How it works
The thick body of soil absorbs impact energy by local crushing and plastic deformation of the fill. A steep uphill face, often of reinforced soil or gabions, stops blocks from rolling over the crest. A ditch on the uphill side collects fallen material.
Types
- Plain earth bunds
- reinforced soil embankments with geogrid or steel mesh facing
- gabion-faced embankments
- embankments with tyre or sand cushion facing
Materials
Compacted granular fill, geogrid or welded mesh reinforcement, gabion or wrapped facing, drainage layers and erosion protection on the downhill face.
Height and position come from rockfall trajectory analysis that gives bounce heights and energies along the slope. The uphill face is made steep so blocks cannot climb it, and the crest has freeboard above the design bounce height. The body must resist punching and overall sliding, and its foundation must be stable. Space for the catch ditch and access for clearance are planned from the start.
Installation and QA steps
- Survey and clear the site, provide access for plant.
- Prepare and drain the foundation.
- Place and compact fill in layers with reinforcement at specified spacing.
- Build the facing and check its line and steepness.
- Form the uphill ditch and the downhill erosion protection.
- Inspect after major events and clear collected debris.
- Blocks overtopping where the crest is too low for actual bounce heights
- facing damage from repeated impacts
- ditch full of debris so new blocks roll over
- erosion or slip of the downhill face
Codes cited
- BS 8006-1 (UK): Code of practice for strengthened/reinforced soils and other fills.
Cited by number only. We do not reproduce code text, tables or figures.
Related
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