2016 john mitchell lecture presented to ygg 11.04...2004/11/01 · thermal profiling deep...

Notes of presentation to YGG 11.04.2017

12/04/2017

1

Institution of Civil EngineersJohn Mitchell Lecture Registered charity number 210252. Charity registered in Scotland number SC038629.

2016 John Mitchell Lecture

– presented to YGG 11.04.17

Presented by Dr Martin Pedley

Joh

n M

itch

ell L

ectu

re

Inst

itu

tio

n o

f C

ivil

En

gin

eers

Institution of Civil EngineersJohn Mitchell Lecture

Personal journey

Establishment of soil nailing in UK

Deep foundations – progressive development

Risk and cycle of re-learning

Developments in foundation engineering – a personal perspective


12/04/2017

2



Foundation &business Risk management

Design Engineer

Joint Venture Manager

Technical management

Foundation design & research

Sitesupervision

Researchstudent

Industrial trainee1985

2015


Historical perspective

Fundamental research and validation of interactions

Challenge of developing standards

Soil nailing – establishment in the UK


12/04/2017

3


Soil nailing – example




12/04/2017

4






12/04/2017

5




Soil nailing – historical perspective


12/04/2017

6


Soil nailing – soil reinforcement interaction




12/04/2017

7


Axial component Shear component





12/04/2017

8


S

X

Seffect of nail


S + S

X

Y

V AS

axS

Pax

PS



V AS

Z

ELEVATION

L

V AS

500mm 500mm

PLAN

250mm

250mm

500mm

Reinforcement


12/04/2017

9



Jewell &Pedley (1990a)

Brinch Hansen& Lundgren (1960)

‐1 1 ‐0.03 0.03 0.06

LateralStress (/b)

ShearForce (PS/PP)

s2

s2

‐1

0.5

11

b

(z/L) (z/L)(z/L)

1

BendingMoment (M/MP)


Soil nailing – model validation through full scale test data (after Gassler)


12/04/2017

10


V

H

L

R , f(V , H, L)



Soil nail standards – maturing of the technique?


12/04/2017

11


Differences in foundation construction

Capabilities – larger and deeper

Analysis – Buildability – Standards balance




DeeperNew geologies

Structural complexity and scale


12/04/2017

12


Deep foundation - construction safety


1985 2015

Retaining walls

Bearing piles

Design analysisand codes

Materials

Testing

25 – 35m deep1.0 – 1.2m thick

30 – 40m deep900 – 1,500mm

Spring stiffnessBritish StandardsFPS

Rebar 25 – 40mmConcrete 30 – 40N/mm²Bentonite

Reaction pilesSonic coring

30 – 50m deep1.2 – 1.5m thick

40 – 60m deep900 – 2,500mm

Finite elementEN’sICE SPERW

Rebar 32 – 50mmConcrete 45 – 50N/mm²Bentonite/Polymers

Bidirectional jacksThermal profiling



12/04/2017

13




12/04/2017

14


1985 2015

Retaining walls

Bearing piles


Materials

Testing

25 – 35m deep1.0 – 1.2m thick

30 – 40m deep900 – 1,500mm




30 – 50m deep1.2 – 1.5m thick

40 – 60m deep900 – 2,500mm







12/04/2017

15



1985 2015

Retaining walls

Bearing piles


Materials

Testing

25 – 35m deep1.0 – 1.2m thick

30 – 40m deep900 – 1,500mm




30 – 50m deep1.2 – 1.5m thick

40 – 60m deep900 – 2,500mm




Deep foundations – development progression


12/04/2017

16



1985 2015

Retaining walls

Bearing piles


Materials

Testing

25 – 35m deep1.0 – 1.2m thick

30 – 40m deep900 – 1,500mm




30 – 50m deep1.2 – 1.5m thick

40 – 60m deep900 – 2,500mm






12/04/2017

17



1985 2015

Retaining walls

Bearing piles


Materials

Testing

25 – 35m deep1.0 – 1.2m thick

30 – 40m deep900 – 1,500mm




30 – 50m deep1.2 – 1.5m thick

40 – 60m deep900 – 2,500mm






12/04/2017

18




12/04/2017

19


Why do problems get repeated?

Generational cycles and missing knowledge

Possible solutions and best practice



Each “generational cycle” our capability moves on– improved analysis tools– updated specifications and standards– better training– more advanced machinery and

technology

Why do we repeat past lessons?



12/04/2017

20


Rediscovering concrete


Analysis

Codes and standards

Buildability trials, research & full scale monitoring

Industry collaboration

Knowledge accessibility

People factors

Risk and cycle of re-learning – possible solutions


12/04/2017

21


Projects will increase in complexity – the ground will continue to challenge and surprise

To manage risk we need to maintain a good balance between analytical capability, buildability and relevant codes & standards

Knowledge can easily become hidden requiring later re-discovery

Trials, full scale monitoring and research are all important in providing data to validate and calibrate incremental progress



BGA and ICE for the recognition provided in awarding the John Mitchell Medal

Current and former colleagues in Cementation Skanska and Skanska UK, including Rab Fernie, David Greenwood and the late Ken Fleming

Opportunities and motivation provided whilst at University of Surrey and University of Oxford

The many industry collaborators met through Federation of Piling Specialists, CIRIA and BSI in developing best practice

Acknowledgements


12/04/2017

22



Deep foundation construction – safety

2016 john mitchell lecture presented to ygg 11.04...2004/11/01 · thermal profiling deep...

Documents