Underground Works Substructure Earth Retaining Diaphragm wall

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Underground WorksSubstructure Earth Retaining
Diaphragm wall
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Failure of retaining wall systems
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Underground works
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TYPES OF EARTH RETAINING SYSTEMS FOR EXCAVATIONS

• Natural Slope
• Gravity Walls
• Reinforced Soil with Geo-synthesis
• Braced Walls or (mostly) strut support
• Soldier pile and lagging walls with anchor or
  strut support
• Sheet piling or sheet pile walls with anchor or
  strut support
• Pile walls (contiguous, secant) with anchor or
  strut support

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TYPES OF EARTH RETAINING SYSTEMS FOR EXCAVATIONS

• Diaphragm walls or slurry trench walls with
  anchor or strut support
• Prefabricated diaphragm walls with anchor or
  strut support
• Reinforced Concrete (Cast-in-situ or
  prefabricated) retaining walls (Excavation in
  stages) mostly anchor support
• Drop shaft sinking and caissons
• Jet-grout walls (or deep soil mixing) Anchors
  or Struts
• Soil nail walls
• Top-down excavation and support method

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Wall Selection Criteria

• 1.Size of excavation
• 2.Ground condition
• 3.Groundwater level
• 4.Settlement of adjacent ground
• 5.Displacement criteria
• 6.Others (Availability, Speed of Work etc.)

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1.Natural Slope
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2.Gravity Walls
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3.Geo-synthesis Geotextile/Geogrids
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4.BRACED WALLS ANCHOR/STRUT SUPPORT

• Excavation step by step
• Steel frames with timbering or shotcrete
  (sometimes timber frames)
• Usually strut support
• Soils with some cohesion and without water table
  are suitable
• Often limited to small dimension shafts and
  trenches with and without penetration below base
  (mostly without)

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BRACED WALLS STRUT SUPPORT
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Soldier pile and lagging walls
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5.SOLDIER PILE AND LAGGING WALLS (Example BERLIN
WALLS)
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SOLDIER PILE AND LAGGING WALLS (use tieback)
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6.SHEET PILE WALLS (SHEETPILING)
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Sheet Piles
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Plan viewElevation
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Retaining wall system Plan
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Proper Interlock
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Transportation
Pre-loading
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Bad shoring
Becareful
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Weak ?
Checking?
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For what?
Heavy equip.
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7.PILE WALLSTangent pile
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Failure of piles wall system
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Tangent secant pile
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8.DIAPHRAGM WALLS (Slurry Trench Walls)
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Barratte piles/D-wall
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D-Wall Guide Wall
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CRAB
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Crab
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D-wall diagram
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D-wall of Subway Station
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Steel cage
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Steel cage installation
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Water stop
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Water stop
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9.Prefabricated Diaphragm Walls
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10.Reinforced Concrete(Cast in-situ or
prefabricated) Retaining Walls
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Type of Caissons
Open Caissons Pneumatic Caissons
Box Caisson (floating)
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11. Jet Grout walls or other soil methods like
deep soil mixing
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12. Soil Nail Walls
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Soil Nail (Anchor)
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Soil nail machine
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Test performance
Drilling Monitoring
Sonic Integrity Test
Inclinometer Monitoring
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Soft clayWater.
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Below the Manhole
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Good Sheet pile and Wale contact
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Steel box piles
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Coffer Dam
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Top/Down construction

• What benefits?
• Is it suitable for Bangkok?
• Example buildings used this system.

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Above and below
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Down progress
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Connection/Joint