E E N N G G N N E E I I E E R R S S Colluvial Deposits Colluvial Deposits E E N N G G N N E E I I E E R R S S Geohazards in Transportation Geohazards in Transportation In the Appalachian Region In the Appalachian Region Exploring and Constructing Exploring and Constructing on Sites Underlain by on Sites Underlain by Colluvial Deposits Colluvial Deposits in the in the Eastern Kentucky Coalfields Eastern Kentucky Coalfields Colluvial Deposits
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Exploring and Constructing on Sites Underlain by Colluvial ... · Rockline S.I. DatumS.I. Datum 1.0” S.I. Datum Slope Inclinometer Scale Slope Inclinometer Movement Slope Inclinometer
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EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
Colluvial DepositsColluvial Deposits
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
Exploring and ConstructingExploring and Constructingon Sites Underlain by on Sites Underlain by
Colluvial Deposits Colluvial Deposits in thein the
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
!! Typical initial assumptions in preparing Typical initial assumptions in preparing subsurface explorations of highway cuts in subsurface explorations of highway cuts in Eastern KentuckyEastern Kentucky
!! Typical actual conditions and cut slope designTypical actual conditions and cut slope design!! Cut slope design within Cut slope design within atypicalatypical bedrock bedrock
conditions conditions !! UhUh--oh, where is bedrock?oh, where is bedrock? Welcome to Welcome to
colluvium colluvium !! Deposition of colluviumDeposition of colluvium!! Design of cut slopes in colluvial depositsDesign of cut slopes in colluvial deposits!! SummarySummary
Presentation OutlinePresentation Outline
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
Typical Initial Assumptions in Preparing Typical Initial Assumptions in Preparing Subsurface Explorations of Highway Subsurface Explorations of Highway
Cuts in Eastern KentuckyCuts in Eastern Kentucky
Roadway Roadway TemplateTemplate
Assumed Cut Slope Line Assumed Cut Slope Line (1.2H:1V) to Determine (1.2H:1V) to Determine Approximate Top Approximate Top Boring LocationBoring Location
Existing Existing GroundlineGroundline
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
Geologic Cross Section of Pine MountainGeologic Cross Section of Pine Mountain
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
Rock Disintegration Rock Disintegration Zone (RDZ)Zone (RDZ)
Cut Slope Design Within Atypical Cut Slope Design Within Atypical Bedrock ConditionsBedrock Conditions
23 degree 23 degree DipDip
Roadway Roadway TemplateTemplate
Assumed Cut Slope Line (1.2H:1V) to Determine Top Boring Location
Assumed Cut Slope Line Assumed Cut Slope Line (1.2H:1V) to Determine (1.2H:1V) to Determine Top Boring LocationTop Boring LocationRecommended Recommended
Cut Slope DesignCut Slope Design
Existing Existing GroundlineGroundline
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
UhUh--oh, Where is Bedrock?oh, Where is Bedrock?
Existing Existing GroundlineGroundline
Roadway Roadway TemplateTemplate
Assumed Cut Slope Line (1.2H:1V) to Determine Top Boring Location
Assumed Cut Slope Line Assumed Cut Slope Line (1.2H:1V) to Determine Top (1.2H:1V) to Determine Top Boring LocationBoring Location
Recommend Cut Slope Recommend Cut Slope (Coincident with Interpolated (Coincident with Interpolated
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
Deposition of ColluviumDeposition of Colluvium
Talus: coarse debris, accumulates on a slope Talus: coarse debris, accumulates on a slope at the foot of a cliff as a gravity deposit.at the foot of a cliff as a gravity deposit.
Colluvium: a mantle of loose material that Colluvium: a mantle of loose material that moves by creep down a hillside. moves by creep down a hillside.
BedrockBedrockTalusTalus
BedrockBedrockBedrockBedrock
In some places creep is indicated by the In some places creep is indicated by the bending of trees.bending of trees.
ColluviumColluvium
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
One EngineerOne Engineer’’s Opinion Ons Opinion On……
……How Colluvium was Deposited in How Colluvium was Deposited in the Eastern Kentucky Coalfieldsthe Eastern Kentucky Coalfields
Shale (Typ.)Shale (Typ.)
Coal (Typ.)Coal (Typ.)
Sandstone (Typ.)Sandstone (Typ.)
ColluviumColluviumTalusTalusCreepCreep
Shale (Typ.)Shale (Typ.)
Coal (Typ.)Coal (Typ.)
Sandstone (Typ.)Sandstone (Typ.)
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
Exploration and Design of Cut Slopes Exploration and Design of Cut Slopes in Colluviumin Colluvium
Belfry Landslide Next to U.S. 119 Belfry Landslide Next to U.S. 119 Pike County, KentuckyPike County, Kentucky
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
Belfry Landslide Belfry Landslide –– Available Geological Available Geological Information Information
……to Determine Approximate Failure Plane Location and to Determine Approximate Failure Plane Location and Calculate Residual Shear Strength of ColluviumCalculate Residual Shear Strength of Colluvium
To U.S. 119To U.S. 119
Existing GroundlineExisting Groundline
8989’’
6161’’
8989’’2121’’
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
CasingCasing CasingCasing Casing InstallationCasing Installation Probe and CableProbe and Cable
Probe Inside CasingProbe Inside Casing Readout / RecorderReadout / Recorder Inclinometer Data PlotInclinometer Data Plot
EE NN GG NN EEII EE RR SSGeohazards in Transportation
In the Appalachian Region Geohazards in Transportation Geohazards in Transportation
In the Appalachian Region In the Appalachian Region
!! Undisturbed Colluvium deposits are metastable due to the nature Undisturbed Colluvium deposits are metastable due to the nature of of their depositiontheir deposition
!! Most of the deep soil deposits encountered on the hillsides of Most of the deep soil deposits encountered on the hillsides of Appalachia are probably ColluviumAppalachia are probably Colluvium
!! The composition of this Colluvium varies significantly horizontaThe composition of this Colluvium varies significantly horizontally and lly and vertically within a few feet, if not a few inches vertically within a few feet, if not a few inches
!! It is impractical to evaluate the shear strength of Colluvium usIt is impractical to evaluate the shear strength of Colluvium using ing standard testing methods standard testing methods
!! Slight changes to the geometry and/or ground water conditions ofSlight changes to the geometry and/or ground water conditions of the the slopes underlain by Colluvium can cause displacement or failureslopes underlain by Colluvium can cause displacement or failure
!! Three options to modify or stabilize Colluvium deposits on hillsThree options to modify or stabilize Colluvium deposits on hillside:ide:•• Complete removal of undisturbed or failed depositsComplete removal of undisturbed or failed deposits•• Install retaining structure socketed or anchored in bedrock to Install retaining structure socketed or anchored in bedrock to
prevent movementprevent movement•• Regrade slope based on Slope Inclinometer information when slopeRegrade slope based on Slope Inclinometer information when slope
failure has already occurredfailure has already occurred