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8/17/2019 04-Ansari PPT.pdf
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Slope Support Design & Performance
1Nadir Ansari & M. Janes, P.Eng.2
Slope Support and Design
Presentation Schedule:• Problem definition
• es gn osop y
• Outcomes:
• CN Grimsby
• Castlefield Lowe’s
• Whitemud Hwy
• Monitoring Program
2
• Summary & Discussion
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Problem Definition
When is it Slope Support vs Shoring?
• When the slope is preserved long term
• New structures support the slope
• When the slope is reinforced
3
Slope Support and Design
Design Philosophy
1. Excellence in geotechnicalinvestigation and testing
2. Advanced analytical methods
1. Caveat – know the answer first
3. Design to the probable, not the
worst case
4
4. Excellence in monitoring
5. Constant calibration
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Slope Support and Design
Design Philosophy
“Large savings can often be made by designing on thebasis of the most probable rather than the mostunfavourable possibilities. The gaps in the availableinformation are filled by observations duringconstruction and the design is modified in accordancewith these findings.”
5
Terzaghi and Peck
Slope Support and Design
CN Grimsby
• uppor uns a e s ope
• Weak fills, uncompacted embankment
• Moving slope
• Maintain rail right of way
• Low impact to neighbours
6
• Arrest slope movements
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CN Grimsby
• Non reticulated Micropile wall with cap
• Poor access
• No re-grading of slope allowed
• Low construction slope loading
• FEA analysis - FLAC
•
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• movement reduction
CN Grimsby
8
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CN Grimsby
9
CN Grimsby
10
FEA original condition: Slough and plastic failure x
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CN Grimsby
11
Non reticulated Micropile wall with cap
CN Grimsby
12
Non reticulated Micropile wall cap
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CN Grimsby
13
Reduced movement & no plasticity
Slope Support and Design
Whitemud Hwy Development
• uppor s ope – ex s ng s e,
• Maintain highway right of way
• Increase slope steepness 3:1 to 2:1
• Arrest slope movements
14
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Whitemud Original Slope
15
Whitemud
16
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Whitemud
• Path to permanent was temporary
• Shotcrete support wall to allow:
• Caisson bench installation
• Integrating, cascading, ringed footings
17
• CIP orses oe arcs a ove gra e
• Oops a weak layer !
Whitemud
Original condition with bin walls 3:1 slope
ro ec ca e or s eepen ng o : s ope
Final walls of integrated arcs
Proposed geometry
18
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Whitemud
Permanent wall incorporatedCIP inte rated arcs
Both footings and walls above
Caissons & Anchors thru weak zone
19
Whitemud
20Construction underway
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Whitemud
21Injection anchor installation
Whitemud
Failure during construction
along weak clay seam plane - 25°
Remediation required early installation
of caissons and permanent anchors
22
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Whitemud
Inclinometer
Data
23
layer at 8 m
depth
Whitemud
24Failure interrupts construction sequence
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Whitemud
25Forming of caisson supported step ring footing
Whitemud
26Completed arc structure prior to backfill
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Slope Support and Design
Castlefield Lowe’s Development
• xcava e n o ex s ng s ope
• Aesthetic final slope treatment
• Large radii corner accommodates
truck turning radius
• Maintain tower & roadwa above
27
• Increase overall slope steepness
Castlefield Lowe’s
28Site prior to excavation
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Castlefield Lowe’s
Plan of wall
within
constrained
area
29
Castlefield Lowe’s
Classical Rankine analysis of loads
e eory:
Allowed ‘dissipation’ of load within shell
Supported load through:Skin friction between wall and soil,
Added anchor capacity as easement permitted
Sloped wall face
30
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Castlefield Lowe’s
31
Castlefield Lowe’s
32
Elevation of high constrained area
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Castlefield Lowe’s
33
Castlefield Lowe’s
Post tensioned shotcrete to control movement
Double layer:
Base 150 mm for strength
Overlay 100 mm thick coloured
shotcrete façade
Attention to drainage above and behind wall
34
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Castlefield Lowe’s
35
Castlefield Lowe’s
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Wall onstruction Detail
Concern regardingfrost action
thickening of wall at
anchor head
Difficult detail to
attain in field with
draina e material
37
Wall onstruction Detail
Top of wall detail: swale &
fence
: v
drainage panels & perimeter
toe drain
38
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onstructability
39Swale installation
Castlefield Lowe’s
40
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Castlefield Lowe’s
41
Castlefield Lowe’s
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Slope Support and Design
Monitoring:
. xce ence n mon or ng qua y
2. Best possible accuracy & precision
3. Timely results & reporting
4. Site & problem specific
43
5. The proof is in the performance
Slope Support and Design
Summary
• Client,Site,Problem specific solutions
• 3 problems - 3 solutions
• Attention to environmental effects
• Climate
• Corrosion
• Monitorin to establish & enhance
44
performance as required
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Slope Support and Design
Acknowledgements•
www.hcmatcon.ca
• Geo-Foundations Contractors
www.geofoundations.ca
45
.