Download - Mechanisms and mitigation of highway landslide collapse in indiana by by Malek Smadi of GEOTILL
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Mechanisms and Mitigation
of Highway Landslide
Collapse in Indiana
100th Annual Road School 2014
3/12/2013
Malek Smadi, Ph.D., P.E.
Principal Engineer - GEOTILL - Fishers, IN
[email protected] - www.geotill.com
Joey Franzino, P.E.
Operations Engineer - INDOT
[email protected] - www. indot.in.gov
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CONTENTS
1. Geologic Conditions
2. Landslide Areas
3. Landslide Types
4. Timing of Landslides
5. Potential Slide and Steep
Slope Areas
6. Purpose of Geotechnical
Evaluations
7. Improvements Related To
Landslide Type
a. Surface Water Improvements
b. Groundwater Improvements
c. Light Weight Fill
d. Retaining Structures
e. Soil Reinforcement
f. Grading
8. Case History
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Geologic Conditions in Indiana
Oldest Bedrock
Youngest Bedrock
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Geologic Conditions in Indiana
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Correlation of Landslide Occurrence & Geology
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Groundwater and Wet Weather
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Landslide Types in Indiana
There are four general landslide-type possibilities in Indiana:
High bluff peeloff
Groundwater blowout
Deep-seated
Shallow colluvial
There are various combinations of these generalized landslide types,
as one type of mechanism may lead to another during the sliding, or
the slide may be complex, exhibiting different modes of failure in
different portions of the slide.
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High Bluff Peeloff - Landslide Types in Indiana
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High Bluff Peeloff - Landslide Types in Indiana
US 50
Ripley
County
Gabion
Wall
Failure
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High Bluff Peeloff - Landslide Types in Indiana
US 50
&
US 241
Gabion
Wall
Failure
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High Bluff Peeloff - Landslide Types in Indiana
US 50
&
US 241
Gabion
Wall
Failure
14 HP 89 sections - 410 ft long - spaced 6 ft center-to-center
Extend 10 ft into sound bedrock
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High Bluff Peeloff - Landslide Types in Indiana
SR 66
Spencer
County
Re-Grading
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High Bluff Peeloff - Landslide Types in Indiana
SR 66
Spencer
County
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High Bluff Peeloff - Landslide Types in Indiana
SR 66
at
66.3RP
Re-Grading
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Groundwater Blowout - Landslide Types in Indiana
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Groundwater Blowout - Landslide Types in Indiana
SR 237
1.05RP
Tell City
El 544
El 436
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Groundwater Blowout - Landslide Types in Indiana
SR 237
1.05RP
Tell City
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Groundwater Blowout - Landslide Types in Indiana
SR 1
Old
Road
in
Cedar
Grove
We lost 3/4 of the road in this rain event.
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Groundwater Blowout - Landslide Types in Indiana
SR 1
Old
Road
in
Cedar
Grove
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Groundwater Blowout - Landslide Types in Indiana
SR 1
Old
Road
in
Cedar
Grove Needs
toe protection
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Deep-Seated - Landslide Types in Indiana
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Deep-Seated - Landslide Types in Indiana
I-74 Landslide Geofoam
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Deep-Seated - Landslide Types in Indiana
I-74 Landslide Geofoam
20 ft high
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Deep-Seated - Landslide Types in Indiana
I-74 Landslide Geofoam
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Deep-Seated - Landslide Types in Indiana
I-74 Landslide Geofoam
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Deep-Seated - Landslide Types in Indiana
I-74 Landslide Geofoam
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Deep-Seated - Landslide Types in Indiana
SR 37 RP 11.4 Perry
County
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Deep-Seated - Landslide Types in Indiana
SR 37 RP 11.4 Perry
County
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Deep-Seated - Landslide Types in Indiana
SR 37 RP 11.4 Perry
County
550 piers, 30 inches in diameter – 28 to 30 ft deep
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Deep-Seated - Landslide Types in Indiana
SR 37 RP 11.4 Perry
County
Rip-rap key was placed two feet within the competent sandstone bedrock
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Deep-Seated - Landslide Types in Indiana
SR 37 RP 11.4 Perry
County
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Deep-Seated - Landslide Types in Indiana
SR 37 RP 11.4 Perry
County
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Deep-Seated - Landslide Types in Indiana
US 50 Slide at SR 62
Replacing the fill
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Deep-Seated - Landslide Types in Indiana
SR 37 RP 11.4 Perry
County
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Deep-Seated - Landslide Types in Indiana
SR 46 RP 150
Dearborn County Drilled
Shaft Wall
In 1952 bin-wall was constructed
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Deep-Seated - Landslide Types in Indiana
SR 46 RP 150
Dearborn County Drilled
Shaft Wall
Drilled shaft with tiedback 4 ft in diamter - 7 ft center to center – 40 ft deep
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Deep-Seated - Landslide Types in Indiana
SR 46 RP 150
Dearborn County Drilled
Shaft Wall
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Deep-Seated - Landslide Types in Indiana
SR 56 Switzerland
County Vevay
Drilled Shaft Wall
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Deep-Seated - Landslide Types in Indiana
SR 56 Switzerland
County Vevay Drilled
Shaft Wall
2000 ft long wall
300 drilled shafts with
tied-back
3 ft in diameter
8 ft center to center
5 ft into the bedrock
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Deep-Seated - Landslide Types in Indiana
US 150
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Deep-Seated - Landslide Types in Indiana
US 150
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Shallow Colluvial - Landslide Types in Indiana
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Shallow Colluvial - Landslide Types in Indiana
US 50
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Shallow Colluvial - Landslide Types in Indiana
US 41 RP
57+20
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Shallow Colluvial - Landslide Types in Indiana
Mixture being spread over geotextile
Slide Correction on I-74, 7/10th mile east of SR1 and I-74
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Case History S.R. 237 in Perry County, IN
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Indiana Road Map
Project location
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General Site Plan
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Aerial View of the Site
Slide Area
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S.R. 237 was originally built in 2003. This particular slope is approximately one-half mile long and was designed to be 2:1 and up to 112 feet high.
Original Roadway Construction
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Geotechnical Challenges
High embankment fills
Slopes designed as steep as 2:1, placed on sloping natural ground
Variations in rock surface elevations
Fills consist of soils, shale and sandstone
Environmental constraints
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Slope after original construction.
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First Slope Failure
In May 2010 during heavy rain, the slope moved.
The road edge and guardrail experienced vertical displacement.
Northbound driving lane closed.
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First Slope Failure
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First Slope Failure
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First Slide
Possible causes for the first slide:
Actual slope measured steeper than 2:1 with the height of 112 feet, combined with the type of fill used (co-mingled soil and shale) was unstable.
Possible inadequate benching.
Water pouring from slope (excessive groundwater).
Heavy rainfall in spring.
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Boring location plan for the first slide.
First Slide
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First Slide Correction in 2010
A soil nail wall with a design-build contract requiring a seven year warranty.
Extend outlet drainage pipe to the toe of the east slope.
The contractor proposed a new H-pile encased in concrete wall with tiebacks and a shotcrete facing after the bid which was accepted by INDOT.
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First Slide Correction in 2010
Contractor’s Design
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After First Correction
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In April 2012 during heavy rain, the slope in front of the wall moved. It gradually dropped vertically approximately 12 feet due to new failure.
Second Slope Failure
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Second Slope Failure
Roadway Existing Slope
Tie Back Wall
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Second Slope Failure
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Second Slope Failure
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Second Slope Failure
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Possible causes for the second slide:
Surface slide triggered by heavy rainfall.
Failure of outlet pipe of spring box which was buried underneath the roadway.
Insufficient investigation after the first slide (Borings were only 40 feet deep.)
Second Slide
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Second Slide
Boring location plan for the second slide.
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Phase-1 Design
Drainage correction: includes spring box repair & horizontal drains
Phase-2 Design
Rock backfill (chosen)
Three tier soil nail walls
Design for Second Slide
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Correction Using Rock Backfill
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Correction Using Three Tier Wall
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Problems With Rock Backfill
Slide aggravated further after letting in March 2013 due to heavy rains.
Massive amount of water seeped out of the slope.
The rock backfill was not viable option anymore because it would require the 1:1 temporary slope.
Potential destabilization of existing soldier pile wall.
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Problems With Rock Backfill
Another Surprise:
During exploratory excavation for the spring box repair, coal mine shafts were uncovered.
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Mine Shaft Discovery
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Mine Shaft Discovery
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Mine Shaft Discovery
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More Investigation
Resistivity study done to search for mines.
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Map of Resistivity Lines
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Resistivity Study Results
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More Investigation
Resistivity study done to search for mines.
More borings to verify the locations of suspected mines under the roadway as per geophysical study (resistivity testing).
Borings reveal several collapsed mine shafts under roadway.
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Phase-1 Design
Drainage correction
Mine shaft interceptor drain
Grout the mine shafts
Phase-2 Design
Drilled pier (3 ft. dia.) with tieback socket into rock
Revised Solution
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Interceptor Drains
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Design Cross Section
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Drilled Shafts and Drain Layout
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Drainage Correction
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Grouting to Fill Mine Shafts
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The new drilled pier wall was originally proposed to be 15 feet from the existing wall.
The construction of new drilled pier wall affecting the integrity of existing soldier pile wall.
Constructability Concerns
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Move the proposed drilled pier wall 40 ft away from existing soldier pile wall (25 ft further) to provide safe excavation for inside lagging and backfill.
Change temporary casing to a permanent casing for drilled piers due to possible co-mingled fill material.
Provide casing for tieback un-bonded length to avoid major loss of grout due to unclassified fill material.
Additional Changes to the Design
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Questions ?
Malek Smadi, Ph.D., P.E.
Principal Engineer - GEOTILL - Fishers, IN
[email protected] - www.geotill.com
Joey Franzino, P.E.
Operations Engineer - INDOT
[email protected] - www. indot.in.gov