Micropiles have been used since the 1950s but faced challenges in adoption in Southeast Asia due to high costs, slow installation, and risks. However, they are well-suited for difficult construction sites with restricted access, deep socketing needs, and high loading requirements. Lessons from challenges include reducing labor costs through mechanization, managing risks through equipment monitoring and site preparation, and improving planning to reduce downtime. Modern micropile rigs and techniques have addressed past challenges and made micropiles a cost-effective solution for difficult ground conditions.

1. 1
MicropilesMicropiles
in Constructionin Construction
ChallengesChallenges
&&
Lessons LearntLessons Learnt
MicropilesMicropiles -- TimelineTimeline
19521952 -- First introduced in Italy for foundationFirst introduced in Italy for foundation
restorationrestoration (underpinning)(underpinning) of WWII damagedof WWII damaged
buildingsbuildings
1960’s1960’s –– Widely used in Europe forWidely used in Europe for
underpinning old sensitive structuresunderpinning old sensitive structures
mid 70’smid 70’s –– First introduced in USA (New York &First introduced in USA (New York &
Boston)Boston)
1980’s1980’s –– Being introduced in East AsiaBeing introduced in East Asia
TodayToday –– ‘Micro‘Micro--mini Revolution’ worldwidemini Revolution’ worldwide

2. 2
MicropileMicropile ApplicationsApplications
Supporting New Loads in Congested AreasSupporting New Loads in Congested Areas
SeismicSeismic RetrofitRetrofit
Arresting Structural SettlementArresting Structural Settlement
Resisting Uplift/Dynamic LoadsResisting Uplift/Dynamic Loads
UnderpinningUnderpinning
Excavation Support in Confined AreasExcavation Support in Confined Areas
Why isWhy is MicropilesMicropiles stillstill
unattractive in the South?unattractive in the South?
Challenges today…Challenges today…

3. 3
ChallengesChallenges
No.1 : High CO$T
RM$150–350 /meter
Price Depends on :
Reinforcement Type
Volume (φ) of hole
Grouting Method (any post grouting)
Location - Accessibility
Length/Quantity of piles
ChallengesChallenges
Why High CO$T?
High Steel (up to 20% As/Ac)
High Labour Cost – Low Prod
Grout (NS) (+admixture) expensive
Fabricate cage in-situ compared to
mass production for precast RC pile
Specialist technology expensive
Few players in the market

4. 4
ChallengesChallenges
No.2 : SLOW
Wash Boring Φ250mm x 25m,
Drag/roller bit, 4T25 cage,
silty soil,3m casing 2 piles/day
-ditto- sandstone/granite socket 2m,
DTH Hammer 2-3 piles/day
ChallengesChallenges
Why Slow
Although Drilling rate alone is high
(e.g. up to 1’/min DTH thru granite)
Adding/Dismantling of Rods manually
Installation/Extract of casing time-consuming
Manual in-situ fabrication of cage on-site
Fixing of couplers, spacers, welding take time
Manual mixing of cement grout
Same machine used for cage installation
High rig breakdown (mostly hydraulic)
Estimation of soil / selection of drill bit
difficult – slow down during drilling
Start-up check/servicing of rig long

5. 5
ChallengesChallenges
No.3a :
Risks
Damage to
public
properties
while
maneuvering/s
etting-
up/drilling.
ChallengesChallenges
No.3b : Risks
Damage to own
equipment:
Rod shears off &
drop into hole.
Rod/DTH gets
stuck in-hole.
Rig gets stuck in
soft soil
Where’s the other half of my
body???
Can the
carwash
take this?

6. 6
ChallengesChallenges
No.4 : Prepare for a
messy, messy, messy mess…
DTH Hammer
Air-Flushing
Dad’s favourite “Pasar
Malam” umbrella…
ChallengesChallenges
Wet, Soggy, Soft ground from wash
boring makes it difficult to maneuver
Help!!! I’ve lost
the last pile we
drilled – can’t
see a thing!
You just
crawled over
it!!
What
now!!!

7. 7
ChallengesChallenges -- YESTERDAYYESTERDAY
Leading to -ve General Perception
You must be
joking.
Too
Expen$ive!
Where a
man can
enter, I
can install
a
Micropile
I know the
PROBLEMS! I
don’t want
to take the
risk.
But the
BENEFITS
blah, blah,
blah…
The Construction Industry TODAYThe Construction Industry TODAY
Complicated StructuresComplicated Structures
Constricted AccessConstricted Access
Confined SpaceConfined Space
Difficult sitesDifficult sites
Special Foundations…..Special Foundations…..

8. 8
But Still – MICROPILES are best
when it comes to DIFFICULT
Special sites!
I need Capacity
but NO Space!
I need 3m
rock
socketing!
I also need high
lateral capacity piles
by this slope.
TODAY
Eureka!
MICROPILE
Boleh!…
Bore pile too BIG
– need something
tiny.
1980
1990
Today
Benefits ofBenefits of MicropilesMicropiles
When you haveWhen you have
problems ofproblems of
low headroomlow headroom
and restrictedand restricted
access…access…
No.1
Reason

9. 9
Benefits ofBenefits of MicropilesMicropiles –– No.1No.1 ReasonReason
Low Headroom /Low Headroom /
Restricted AccessRestricted Access
ProblemProblem
Ho Chi Minh City –
District 1
Restricted Access?Restricted Access?
Proposed 8-storey building….
50’ x 100’ area

10. 10
Benefits ofBenefits of MicropilesMicropiles
No.2 Reason :
High Performance
•Loading fr 3 – 500 tons!
•Higher As/Ac compared to RC Driven pile
As Micropile 4-8% vs As RC Pile <3%
-> Better in Bending, Lateral Loading
Shear resistance, Seismic performance
Benefits ofBenefits of MicropilesMicropiles
High
As/Ac
Good for
High Lateral/
Seismic
Loading
&
Bending

11. 11
Benefits ofBenefits of MicropilesMicropiles
No.3 Reason :
Can Penetrate Anything
• Drilling thru stiff clay, sandstone, timber,
granite (except buried steel).
•Easier penetration in rock compared to bored pile.
By various creative ways of
drilling…
Benefits ofBenefits of
MicropilesMicropiles
By various creative
ways of drilling…
Wash Boring – Roller (Tricone) Bit
Auger
Down Hole Hammer
Buried
Steel

12. 12
Benefits ofBenefits of MicropilesMicropiles
No.4 Reason :
Flexibility
(Many Ways) to adjust to
difficult soils…
• Enhance End Bearing
•‘Cross-Breed’ with other Ground Improvement
technique…
Benefits ofBenefits of MicropilesMicropiles
Flexibility – Suits
the soil, Suits your
needs…

13. 13
Benefits ofBenefits of MicropilesMicropiles
No.5 Reason :
Almost ZERO
Vibration/Noise.
NO Complains!
Lessons LearntLessons Learnt
Lesson 1 :
Micropiles are LABOUR INTENSIVE!
Cost $ can be reduced by :
Reducing Manpower;
•Using Steel Pipes as alternative to rebars - still
gives required As but greatly reduces
manpower 2-3men.
•Use Ready Mix grout for large grouting
quantity with known grouting time.

14. 14
Lessons LearntLessons Learnt
Reducing Manpower;
• Use slurry pump mixer instead of gravity
mixer into agitator tank. A little more
investment goes a long way.
•Use a crane to install steel cages/steel pipes
instead of using the rig’s winch/rotary
•For large quantities & long term job – install a
silo on-site (or get a supplier do so)
•With 2 or more rigs, always work close by &
cut the manpower for drilling helper & assistant
driller.
Typical Manpower RequirementTypical Manpower Requirement
14 men14 men
3 piles/day/rig3 piles/day/rig
TOTALTOTAL
ProductionProduction
2 @ grout mixer2 @ grout mixer
1 @ agitator tank1 @ agitator tank
1 pump operator1 pump operator
11 hosemanhoseman
Grouting etcGrouting etc
1 welder1 welder
2 general workers2 general workers
FabricationFabrication
1x2 driller1x2 driller
2x2 helpers2x2 helpers
Rig (2 No.)Rig (2 No.)
e.g. 100 micropiles, wash bore, φ250mm, 20m, 2 rigs.
Can cut down to
only 8-9 men for
concurrent activity
planning & utilising
ready mix or slurry
pump mixer, steel
pipe & crane.
Production >4
piles/day/rig
Overall cost reduction ~ 20-30% by increased production.

15. 15
Lessons LearntLessons Learnt
In a typicalIn a typical micropilingmicropiling site,site,
factor infactor in 2020--30%30%
time loss due to :time loss due to :
• Breakdowns of rig/pump & other support
equipment.
• Traffic Congestion on-site (accessibility)
• Machines Idling (poor planning) btw
drilling/installation/grouting.
Lesson LearntLesson Learnt 22 –– BreakdownsBreakdowns
Fact : Micropile
drilling rigs can
have up to 30
hydraulic
switches & very
susceptible to
breakdown/
hydraulic
leak/burst.
HydraulicHoses
Ifonebursts…

16. 16
Lessons Learnt 2aLessons Learnt 2a
For small sites,
use simpler rigs
with lower
torque, faster
RPM…
(depending on soil type) e.g.
SI rigs - fewer
breakdowns.
Lessons Learnt 2aLessons Learnt 2a
Small/Constrained sites - SI
Rig/ Portable Drill frame e.g.
‘Jacro’ is the solution!

17. 17
Lessons Learnt 2aLessons Learnt 2a
Small/Constrained sites using SI Rig / Drill Frame
Yangon, Myanmar
SI Rig thru Yangon Soil :
Alluvial soil – Stiff silty CLAY,
Drag bit, φ500mm, 20m
deep, SI Machine – 1-2
piles per day!
In Johor, M’sia:
φ250mm, 20m deep, Drag/Roller bit, soft – medium
clay/marine clay; > 1-1.5 piles per day!
Lessons Learnt 3Lessons Learnt 3
Plan Well – Accessibility & Maneuverity very important…
Crane saves
manpower/r
ig time
Steel casing
instead of
rebar saves
fabrication
Site clean &
well-kept
makes
maneuvering
easy
Small drill rigs
(SI rig) with
high RPM for
easy soil
condition
Concurrent
drilling & work
close together
saves manpower

18. 18
Lessons Learnt 4Lessons Learnt 4 -- PlanningPlanning
Micropiling Stages in Critical Path (Non-concurrent)
1. Setting Out Points + Shifting
2. Drilling, Install casing & ensure hole stability
3. Flushing & Withdrawal of rods
4. Install fabricated rebar
5. Flushing & Grouting
Grouting
Plant
Typical Site SetupTypical Site Setup
Air
Compressor
Water Tank
Grouting
Plant
Fabrication
Yard
Current
Drilling
Location
Preparing to
grout pile
here
Clearing of new
area for setting
out
Drilling
Pump
AccessRd
Entrance/D
elivery

19. 19
Lessons Learnt 4Lessons Learnt 4
Damages to public property/own equipment…
• Make sure you have adequate COVER (+
3rd party – public injury + property)
• Clear the MESS!
• Check drilling rig / pump regularly
• Check for cracks on drilling rods/joints regularly
• Test the ground before bringing in the rig
Golden Site Rule of Thumb:
Where a man can stand on a ground without sinking, a
rig can also enter.
Pressure exerted by your feet = Pressure exerted by rig’s track
Lessons Learnt 5Lessons Learnt 5 ––
Avoid relying solely on experience without theory
Use the RIGHT Drilling Equipment/Tools :
Drilling Rig (Flexible) – Size, Rotary Torque, RPM, maneuverity
Drilling Type – Wash Bore, Dry Auger, DTH
Drill Bit & Rods – Drag Bit, Roller Bit, DTH (flat/convex), Tubex.
Pump – Recirculating fluid – Diaphragm pump / Piston pump.

20. 20
Monitor drilling parameters :
Thrust Force on Drilling bit
Drilling Fluid Flow Rate & Pressure
Rotary/top drive RPM
Rotary/top drive torque
Air Compressor Output Pressure
Recirculating Fluid Viscosity
Why?
Thrust Force : The thrust force is the force acting along the axis of
the drill during cutting. The thrust force plays a significant role in the
buckling of the drill.
Torque/RPM : The Torque/RPM signifies the power needed by the
machine tool to drill the hole. Also, Torque acting on the drill can result
in torsional vibrations affecting hole quality.
Lessons Learnt 6Lessons Learnt 6
Avoid Pile Failures - Avoid Soft Toe
• Clean the TOE – flush well till
CLEAR water appears before
grouting !
• Tremie tube to be fixed at tip of
last casing.

21. 21
Lessons Learnt 7Lessons Learnt 7
ESTIMATING PILE CAPACITY ON-SITE
Wash Boring;
Rate of Drilling 1m in ½ hrs –eqv- SPT N=100
(Linearly proportional 1m in 15min eqv N=50…)
Skin Friction, fs = 2N kN/m2
End Bearing, fb = 400N/3 or 10000 kN/m2
(whichever is lesser)
Where a man can enter, a
micropile can be installed…
Where a micropile can be installed by
man, the pile can be tested by man…
… by the Micro PDA Hammer Rig. !

22. 22
MICROPILES TODAY
Are different from their predecessors…
They are now:
•Cheap – suits your Budget
•Easy/Fast to Install
•High Tech – less labour
•Very High Axial/
Lateral/Bending Capacity
The Future TelescopicThe Future Telescopic MicropilingMicropiling RigsRigs

23. 23
Solutions for the Difficult Ground