Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

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Micropilesan Introduction

GeoProfound Engineering Sdn Bhd

Micropiles - Timeline1952 - First introduced in Italy for foundation restoration (underpinning) of WWII damaged buildings1960�s � Widely used in Europe for underpinning old sensitive structuresmid 70�s � First introduced in USA (New York & Boston)1980�s � Being introduced in East AsiaToday � �Micro-mini Revolution� worldwide

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Micropile Applications

Rock Socketting � where driven piles cannot penetrate.Supporting New Loads in Congested Areas Seismic Retrofit Arresting Structural Settlement Resisting Uplift/Dynamic Loads Underpinning Excavation Support in Confined Areas

Different Types of Micropiles

Flexibility � Suits the soil, Suits your needs�

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Benefits of Micropiles

When you have problems of low headroom and restricted access�

No.1 Reason

Benefits of Micropiles

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

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Benefits of Micropiles

High

As/Ac

Good for

High Lateral/Seismic Loading

Benefits of Micropiles

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�

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Benefits of Micropiles Can penetrate

anything�

Wash Boring � Roller (Tricone) Bit

Auger

Down Hole HammerBuried Steel

Use Down-Hole-Hammer with Air Compressor to drill thru Rock/Granite

Benefits of Micropiles

No.4 Reason :

Flexibility

(Many Ways) to adjust to difficult soils�� Enhance End Bearing

��Cross-Breed� with other Ground Improvement technique�

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Typical Pile Loading Capacity (Geotech+Structural)

Depending on soil & pile structure, some typical working loads :Dia 250mm, Rebar 6T25, 5m socket in Granite rock - (70+ tons)Dia 250mm, API Pipe As/Ac=8%, 40m in soft soils - (100 tons)Dia 150mm, Rebar 3T25, 20m thru soft clay + hard sandy silt end-bearing - (50 tons)

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

In SOIL (Typical Design using SPT Values)

Skin Friction, fs = 2N kN/m2

End Bearing, fb = 400N/3 or 10000 kN/m2

DESIGN PILE CAPACITY

DESIGN PILE CAPACITY

In ROCK (Socketing)

Skin Friction � Use extrapolation of SPT (e.g.Granite N=300-500, Sandstone N=200) fs = 2N kN/m2

Or use Rowe & Armitage (1987):

Skin Fric, fs=0.45 to 0.6(qu)0.5

Zhang & Einstein (1998):

End Bearing, fb = 3.0 to 6.6(qu)0.5

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Structural Capacity of Piles

Typical Reinforcement = Rebar T16, 20, 25, 32

Ultimate Axial Load:fu = 0.4*fcu*Ac + 0.75*fy*As

Example : 6Y25 rebar in 250mm micropile, grout grade 30MPa, fy=500 N/mm2

fu = 1693kN = 169tons

CO$TRM$150�350 /meterPrice Depends on :

Reinforcement TypeRock Socketing ?Volume ( ) of holeGrouting Method (any post grouting)Location - AccessibilityLength/Quantity of piles

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

ProductionTypical ProductionWash Boring 250mm 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

Typical Manpower Requirement

14 men3 piles/day/rig

TOTAL Production

2 @ grout mixer 1 @ agitator tank1 pump operator1 hoseman

Grouting etc

1 welder2 general workers

Fabrication

1x2 driller2x2 helpers

Rig (2 No.)

e.g. 100 micropiles, wash bore, 250mm, 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 >4piles/day/rig

Overall cost reduction ~ 20-30% by increased production.

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Typical 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

Access R

d

Entrance/Delivery

Small Quantity � Small PilesFor small sites,use simpler rigs with lower torque, faster RPM�(depending on soil type)

e.g. SI rigs

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Small/Constrained sites -SI Rig/ Portable Drill frame e.g. �Jacro� is the solution!

Big Quantity, Small machines�

Tmn Kotamas, Kota Tinggi, Johor

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Small Quantity, Big machine�

JB Inner Ring Road

Johor Bahru

Big Quantity, Big machine�

Vibro unit�

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Drilling ToolsDrilling Rig (Flexible) � Size, Rotary Torque, RPM, maneuverity

Drilling Type � Wash Bore, Dry Auger, DTH hammer (Rock Drill)

Drill Bit & Rods � Drag Bit, Roller Bit, DTH (flat/convex), Tubex.

Pump � Recirculating fluid � Diaphragm pump / Piston pump.

Jack-in- Micropile

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Monitor drilling parameters :Thrust Force on Drilling bit Drilling Fluid Flow Rate & PressureRotary/top drive RPMRotary/top drive torqueAir Compressor Output PressureRecirculating 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.

500kV Transmission Line Micropiling Works

b4

T8 Line 2

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

500kV Transmission Line Micropiling Works

After

T8 Line 2

500kV Transmission Line Micropiling Works

T13 Line 2

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

500kV Transmission Line Micropiling Works

T8 Line 2

500kV Transmission Line Micropiling Works

T38 Line 1

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

500kV Transmission Line Micropiling Works

T38 Line 1

500kV Transmission Line Micropiling Works

UpliftLoadTest

Third Arm Engineering Sdn Bhd -Your Ground Improvement Solutions

Tel : 016-7236492, 07-2364932

Solutions for the Difficult Ground

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