IHNC Flood Protection Geotechnical Challenges

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IHNC Flood Protection Geotechnical Challenges
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Ancient Modern Courses of the Mississippi River
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Long-Term Relative Subsidence Rates Derived from
Radiocarbon Dating of Buried Peat Deposits
USACE, NOD 1995
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Thickness of Holocene Deposits
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B
C
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Generalized Stratigraphy Soil Properties
Ground surface El. 0
Peat, ? 85 pcf, c 150 psf, w 300,
Swamp? 95 pcf, c 200 psf, w 100
Soft organic clay ? 100 pcf, c 200-400
psf, w 160

Interdistributary and Prodelta clay ? 105 pcf,
c 400-800 psf, w 40 to 60 , PL20, LL 70
-50 to -70
Nearshore Gulf sand overlying Pleistocene Clay ?
115 pcf, c gt 1,000 psf
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New Subsurface Investigation
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DESIGN CONSIDERATIONSEARTHEN STRUCTURES

• SLOPE STABILITY
• UNDERSEEPAGE
• SETTLEMENT
• FOUNDATION STRENGTH GAIN
• SUITABLE MATERIAL AVAILABILITY
• ACCESS AND HAUL ROADS
• CONSTRUCTION UNDER WATER

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DESIGN CONSIDERATIONSROCK DIKES AND BREAKWATERS

• BEARING CAPACITY
• SETTLEMENT
• ROCK AVAILABILITY
• FLOTATION CHANNELS

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DESIGN CONSIDERATIONSSTRUCTURES

• PILE CAPACITY
• SHEET PILES
• SETTLEMENT
• NEGATIVE SKIN FRICTION
• UNDERSEEPAGE CUTOFF
• GLOBAL STABILITY
• ANCHOR IN THE PLEISTOCENE
• ACCESS

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Protected Side
Flood Side
Orleans Avenue Interim Closure Structure
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GEOTECHNICAL DESIGN TOOLS

• CONVENTIONAL COMPACTION
• GEOTEXTILES
• STEEL SHEET PILES
• FRICTION PILES
• EXCAVATE AND REPLACE

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NEW DESIGN TOOLS

• SLURRY WALLS
• DEEP SOIL MIXING
• MASS STABILIZATION
• ROLLER COMPACTED CONCRETE
• INTERNAL MECHANICAL STABILZATION

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Questions

• Peter R. Cali, Ph.D., P.E.
• Hurricane Protection Office
• Evans-Graves Team
• Phone [phone]
• E-mail peter.r.cali_at_mvn02.usace.army.mil