Table 5.

Indicative treatment measures matrix for different deterioration transport mechanisms.

TransportmechanismRDAA Class
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Grain ravellingUnlikely to occurCollector drain at crest; diversion drain at toe; debris clearance (e.g. from clogged toe drains)Local reinforced shotcrete application; local mortar screeding; sealing of erosion and fracture chutes; low-growing woody vegetation cover at the slope footWidespread shotcrete or dense vegetation cover to reinforce; limited grascrete or crib wall retentionUnlikely to occur
Stone ravellingOccasional debris clearance and inspectionCut-off drain at crest; rocktrap ditch and fencing; regular scaling and debris and vegetation clearance; local wire nettingExtensive reinforced wire netting; shotcrete or dentition for small, weak areas; masonry support of small overhangs; weepholes for all surface coverInclined drainage; extensive shotcrete, dentition, underpinning or buttressing as needed (with drains); gabions for weak areasBenching with intermediate berms; re-excavation if loose areas caused by blast damage
Block ravellingUnlikely to occurCut-off drain at crest; regular inspection; rocktrap ditch and anchored or reinforced fencing or barrier; regular scaling and debris and vegetation clearance; limited, high-strength wire nettingExtensive reinforced high-strength netting; dentition or masonry walls for weak areas; underpinning of overhangs; weepholes for all surface cover; dowels, bolts or cable lashing for large blocksInclined drainage; underpinning and local buttressing as necessary (e.g. concrete or masonry wall with drainage layer); gabion retention for large loose areas; rockfall shelter; warning signs and restricted accessUnlikely to occur
FlakingUnlikely to occurFrequent debris clearance; cut-off drain at crest; diversion drain at toe; rocktrap ditch; very close mesh wire or plastic nettingSurface protection with geotextiles; widespread vegetation cover (grasses and herbs) in suitable materials; large rocktrap ditch and close mesh fence or protective barrier; seal erosion and fracture chutesRetention with gabion baskets, crib blocks or grascreteStandoff area increased or slope gradient reduced
Wash erosionCut-off drain at crest; diversion drain at toe; regular drain clearanceRegularly spaced weepholes or inclined drains; local surface protection with geotextile membrane for shallow gradients and vegetation cover in suitable materialsSlope drainage; widespread surface protection with geotextiles and vegetation (grasses and herbs); seal erosion and fracture chutes; shotcrete for local weak areas; dentition with weepholes for local cavities and overhangs; low-growing woody vegetation cover at the slope footSurface protection and retention with grascrete (planar slopes only); cross flowpath barriers; underpinning for areas with gulliesSlope angle and length reduced; benching
Solution and karstCollector drainage at crestRegular inspection and removal of vegetationSlope drainage; seal and drain vertical fractures and chutes; mortar screeding or dentition of small cavitiesUnderpinning of large solution cavitiesGrout infilling of large solution cavities
Flexural topplingUnlikely to occurInfrequent inspectionLong-term movement monitoring; seal and drain major vertical fracturesBolting or anchorage of individual key blocks; concrete, masonry or gabion retaining wallsUnlikely to occur
GrainfallUnlikely to occurNo action necessaryLocal surface protection with geotextile matting or shotcreteLimited dentition; sealing of chutes; inclined drainageUnlikely to occur
StonefallInfrequent inspectionScaling of loose blocks; rocktrap fencingDentition and local underpinning for small cavities and overhangs; rocktrap ditch; low-growing woody vegetation cover at the slope footLocal buttressingUnlikely to occur
BlockfallInfrequent inspectionScaling of loose blocks; rocktrap ditch and reinforced fencingDentition and local underpinning for cavities and overhangs; dowels, bolts or cable lashing for large blocksUnderpinning of large overhangs; local buttressing; warning signs and restricted accessUnlikely to occur
Contour scalingInfrequent inspectionRemoval of loose blocksSurface protection with shotcrete or geotextile; containment with wire mesh netting; low-growing woody vegetation at the slope foot or rocktrap fencingInclined drainage; extensive shotcrete applicationUnlikely to occur
Slabfall and topplingInfrequent inspectionScaling of loose blocks; rocktrap ditch and reinforced fencing; movement monitoringDentition and local underpinning for cavities and overhangs; bolts or cable lashing for key blocks; seal vertical fracturesUnderpinning of large overhangs; buttressing; cable reinforcement for potential topplesUnlikely to occur
RockfallUnlikely to occurCut-off drains at the crest; diversion drainage at the toe; inclined drains at critical slope locations; movement monitoring; regular inspection; removal of loose blocks; rocktrap ditch and fenceReinforcement of key blocks with dowels; local underpinning or buttressing; sealing of vertical fractures at the rear of the slope; warning signs and restricted accessSubstantial retention (e.g. crib and gabion walls) and local buttressing; reinforced underpinning of overhangs; rockfall shelterRe-excavation of slope, removing all loose material back to the new surface
Debris flowUnlikely to occurCut-off drainage at crest; diversion drainage at toe; inclined drains at critical slope locations; regular drain and ditch clearance; rocktrap ditch and barrierFor small constituent size: wire mesh netting; local shotcrete; surface cover with geotextiles or vegetation for suitable materials. For large constituent size: dowel reinforcement of key blocks; local underpinning or buttressing; seal vertical fractures at the rear of the slopeRetaining walls (e.g. crib blocks and gabion baskets)Re-excavate slope, scale back to new surface; reduce slope angle and length; cross flowpath barriers
RockslideMovement monitoringInclined drainageAnchor or bolt reinforcement for key blocks; seal critical fractures; toe buttressing or gravity retentionUnlikely to occurUnlikely to occur