1. Mike Turner Applied Geotechnical Engineering
Micropiles – UK Trends
Mike Turner
Applied Geotechnical Engineering

2. Increasing load capacity
1970s & 80s : kN (compression)
[500 kN achievable]
End 1980s : kN common
End 1990s : kN

3. Diameters are also increasing
500kN : mm
1000kN : 190mm (typical)
2000kN: 240mm
- For rock-socketed micropiles

4. Increasing load and diameter

5. 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 mm thick-walled steel tubes
Supported by ground anchors or props

7. Long slender micropiles
High slenderness ratios (length to diameter)
100:1 not uncommon
200:1 installed and load-tested
33 metres long

8. Long slender micropiles – working load and slenderness ratio

9. Long slender micropiles – typical working loads and pile lengths

10. Driven pipe piles G-piles in Sweden (& Northern Europe?)
Dywidag-Systems just introduced systen into UK
Driven ductile cast-iron pipe piles (Type TRM): kN capacity mm 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