Guest-Lecturer Ground Improvement Techniques 2019 PDF

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Guest-Lecturer Ground Improvement Techniques 2019...

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27/03/2019

Ground Improvement Techniques Dr. Gary Chapman Principal Geotechnical Engineer Golder Melbourne

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What is Ground Improvement ?

In place, controlled manufacturing of ground materials to form part of a geotechnical construction system

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Why Use Ground Improvement ? Economics and speed compared to rigid solutions Can treat large areas insitu Can modify ground to meet new design requirements Reduce site risks (settlement, seismic liquefaction) Ground becomes part of an engineered solution Control groundwater/seepage Control pollution Control loss of ground/settlement

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Ground Improvement Techniques Wick drains and / or surcharge Rapid impact compaction, high energy impact rolling Vibro compaction Vibro replacement / stone columns Deep Dynamic compaction/Dynamic replacement Rammed Aggregate piers Deep Soil mixing -wet and dry Grouting ___

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Wick Drains

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Wick drain feed roller

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Surcharge and Wick drains Surcharge to above finished embankment height Can remove most/all of primary consolidation and some (?) creep settlement if you can load more than about 30% more than final fill level Can use wicks (prefabricated flow drains) to accelerate primary consolidation If you have time and fill available this is perhaps the cheapest and easiest form of ground improvement. Stability of surcharged embankments on soft soil is a critical design issue and may require staged construction of surcharge. Instrumentation – settlement monitoring and piezometers can confirm success of surcharging. ___

High Energy Impact Rolling

Requires a large site Angular roller pulled at speed (12 kph) across site Can treat to 2m plus depth (soil type dependent) Useful for proof rolling problematic sites and locating deep soft spots ___

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Rapid Impact Compaction

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Video of RIC Working in NZ

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Vibro compaction

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Keller´s Depth Vibrator S 300

2.6 tons mass 3 m long 300-500 mm diameter 150 kW electric motor Centrifugal Force=30 ton+ Horizontal Amplitude =25 mm

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Measured vibro improvement

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Melbourne vibro example City Rd

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M4 QA Recording system

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Vibro replacement Process Offshore

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Vibro Applications to Soil Types

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Priebe’s Stone Column Design Methodology In situ soil

Ds, Cu, s

Stone columns

+ Dc, c, d, s =

Composite mass

De, Cue, e

• Result: a new composite soil with improved deformation and shear strength parameters • These parameters are used in the stability and settlement analysis ___

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Priebe Method Improvement Factor

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Stone Columns – dry vibro process

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Bottom Feed Vibro replacement

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Stone columns – vibro wet process

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Vibro Replacement – Stone Columns

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Bottom Feed Vibro replacement with grout if required

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Hammered Stone columns • Frankipile system • RAP system

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Frankipile stone column rig

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Rammed Aggregate Piers A ground displacement tool Depths up to 5 m (U.S.) and to 20 m in Europe A dry process (no water) No spoil (  contaminated sites) Use for foundation and slab support and liquefaction mitigation Rapid installation of up to 200 lin. m per day/rig ___

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RAP Working

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Grouted RAPS for Enhanced Stiffness Neat cement grout added during construction  Improves pier stiffness in soft / organic peat soils  Greater support capacity in soft soils 

Ability to stop grout, or build partially-grouted piers

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

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Concrete injected columns (CIC) AKA controlled modulus columns (CMC) or DDC They are not piles! Design with enlarged heads and a load transfer platform Settlement reducers Cost effective, no spoil unlike CFA piles ___

CIC/CMC/DDC Auger head

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Enlarged heads of CIC’s

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Bored Stone Columns

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High Speed Rail Ground Improvement

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VCC-Vibro Compacted Concrete Columns

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Enlarged Heads on VCC’s

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Deep Dynamic compaction

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Compaction Craters

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DEEP SOIL MIXING Wet (grout) or dry (lime &/or cement powder) Rotary or auger mixing Single or multiple axis Increases soil strength and modulus Dry mixing can increase permeabilty

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Deep Soil Mixing

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Lime Column Mixing Head

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DSM Column Strength Testing

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Wet mixing at Docklands

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Large diam DSM Mixing Tool

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CSM Bauer construction equipment

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Grouting Techniques Permeation Grouting Compaction Grouting Compensation Grouting Jet Grouting

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Types of Grouting Compensation grouting

Permeation

Jet grouting

Eroding and mixing the Fracturing of soil with the soi and expanding grout with grout

Grouting Penetrating the voids with grout

TAM

TAM

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Matching Grouting technique to soil type Silt

Sand

Gravel

Stones Jet Grouting

Chemicals

Cement Grout

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Clay

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Chemical Grouting

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Compaction Grouting Low

mobility grout

low

rate of injection high pressure/small stroke pump lifts the ground compresses the surrounding soil

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Compaction Grout

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Compaction Grout Mix Grading Curves 100 % P a s s ing

80 60 40 20 0 0.001

0.01

0.1

1

10

100

Particle Size (mm) CSR excluding fines

lower limit

upper limit

CSR inc cement fines

Ideal

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Driving in compaction grout casing

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Pumping compaction grout

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Excavated compaction grout column

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Sunken crane rail lifting

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Tilted conveyor Transfer House rectification

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Grout injection in progress

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Compaction Grout pipes outside footing

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Compensation Grouting

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Precise Water Level

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Grouting control Panel

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Access Shaft for Compensation Grouting

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Jet Grouting is The erosion of insitu soil materials using a high pressure fluid And

The mixing of the eroded soil insitu with a cementicious binder to form a cement stabilized “soilcrete” material ___

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Jet Grouting History Developed in Japan in 1960’s In Europe, UK and USA since 1970’s Recently introduced to Australia by Keller/Franki who hold super jet license with CGCJ Used on several projects in Sydney to seal walls and underpin buildings First Used on Sydney Airport U/G Station for TBM entry block Perth UG Railway station Box Kingsford Smith Drive Brisbane Base sealing in deep excavations

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Applications for Jet Grouting Retention systems Foundation restoration & underpinning Bored pile wall sealing Sealing of water bearing layers and dam cut offs Deep excavations and shafts Deep slabs and water cut offs ___

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Strength of Jet Grout

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Types of Jet Grouting

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Jet Grouting Aplications

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Jet Grout Slab Sealing

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Jet Grouting Underpinning

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Finished Wall - Trimmed back

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Wall Contact Zone

Manly Site Front Access

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Site Rear Access

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T System Water Jet - 400 bar/100l/min

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T Station

Exposed Jet grout column

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Intimate contact between pile cap and soilcrete linked by grout plug and reo bar/s Lateral resistance provided by grout pile cap connection, but none is required by design

Grout Mixing Station

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Halliburton HT 400 grout pump 500 kW, 300 l/min 400 bar (40 MPa) ___

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Jet Grout sealed CFA Pile Wall

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X Jet System

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Size of Jet Grout Columns

T system

Super jet

X jet

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Thank You!!

Questions (?s) and Answers (!!!s)

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