Micropiles

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Micropiles UK Trends

• Mike Turner
• Applied Geotechnical Engineering

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Increasing load capacity

• 1970s 80s 200-300 kN (compression)
  
• 500 kN
  achievable
• End 1980s 500-600 kN common
• End 1990s 1000-2000 kN

3
Diameters are also increasing

• 500kN 125-160mm
• 1000kN 190mm (typical)
• 2000kN 240mm
• - For rock-socketed micropiles

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Increasing load and diameter
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Diameters are also increasing for micropiles in
soils

• Because small rigs are more powerful
• 450mm diameter piles not uncommon with Klemm and
  Hutte-type rigs
• Blurring divisions between piles and
  micropiles

6
Contiguous micropiled retaining walls

• Increasing use, for
• Restricted sites basements and city-centre
  redevelopments
• Using 140-220mm thick-walled steel tubes
• Supported by ground anchors or props

7
Long slender micropiles

• High slenderness ratios (length to diameter)
• 1001 not uncommon
• 2001 installed and load-tested
• 33 metres long

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Long slender micropiles
working load and slenderness ratio
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Long slender micropiles typical working
loads and pile lengths
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Driven pipe piles

• G-piles in Sweden ( Northern Europe?)
• Dywidag-Systems just introduced systen into UK
• Driven ductile cast-iron pipe piles (Type TRM)
  500-1100kN capacity 119-170mm OD

11
Chance-type piles

• Mechanical auger piles, based upon the Chance
  design
• Very useful on railway infrastructure and mobile
  phone tower installations
• Screwfast piles

12
Ischebeck-type piles

• Self-drilling piles and nails
• Paul Woodfield has more details

13
Dynamic load testing

• As an addition to static load testing
• Mike Turner has more details