Geraci Deep foundations

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ICOG Short Course Compaction GroutingConsensus Guide 01 Introduction 1

Compaction Grouting ConsensusGuide – Short Course

Welcome and IntroductionJeffrey Geraci

Instructors• Dr. Dawn Shuttle, PE

– Chair, Compaction Grouting Consensus Guide Committee

• Joe Harris– Vice President, Hayward Baker, Denver, CO

• Michael Miluski, PE– Owner, Compaction Grouting Services, Inc., Philadelphia, PA

• Jeffrey Geraci, PG, CEG– Sr Eng Geologist, Layne GeoConstruction, Lake Forest, CA

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Course Objectives

• Familiarity with Compaction Grouting Guide• History of Compaction Grouting• Practical Aspects of CG Materials• Familiarity with CG Design• Advances in Compaction Grouting• Field Aspects of Compaction Grouting

Compaction Grouting Overview

• Mechanical process used to densify loose soils• Grout displaces soil in shear• Forces soil grains into tighter packing• Air and water expelled=> pore volume reduced• Treated ground contains stiff grout masses anddensified soil.

• Arguably one of the most sustainable groundimprovement technologies!

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Consensus Guide Development

• Balanced Standards Committee• Balloting at significant milestones• Public comment and review• All ASCE Standards are updated or reaffirmedby the same process every 5 to 10 years.

Compaction Grouting Guide

• Guide is primarily concerned with applicationswhere densification of surrounding soils isprimary objective.

• Intended as a practical guide for specifiers,designers and practitioners.

• Covers field and design and verificationaspects.

• Provides a Guide Specification.

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Compaction Grouting Guide

• Permissive language• Significant judgment left to the reader• CG needs to be applied competently• Not a manual• Not intended as a code of practice

What is Compaction Grouting?• Compaction grouting is a ground improvementtechnique that improves the strength and/orstiffness of the ground by slow and controlledinjection of a low mobility grout.

• Soil is displaced and compacted as the groutmass expands.

• Grout material remains as a growing masswithin the ground and does not permeate orfracture the soil.

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What is Compaction Grouting?• Enables consistent densification around theexpanding grout mass resulting in stiffinclusions of grout surrounded by soil ofincreased density.

• Process can be applied equally well above orbelow the water table.

• Usually applied to loose fills and loose nativesoils that have sufficient drainage to preventbuildup of excess pore pressures.

Compaction Grouting – Short History

• Began in mid 20th Century.• Only major grouting technology to originate inUnited States.

• Today, CG technology is used worldwide.• CG development progressed through theefforts and innovations of many small,independent contractors.

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• 1952: First use by Jim Warner• Need for filling small voids under a structure.• No established technology or equipment to pumpplastic consistency mortar.

• He constructed first “Pump”:– 5’ length of 6” steel pipe w/ 2” hose at base– Wooden piston w/ carpet “seal”– 2X4 lumber for push rod

• 1954: Marvin & Richard Bennett constructed firstplaster pump.

First Prototype Pump 1954

Photo courtesy of Jim Warner

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G1200 Pump 1956

Integral Batch Mixer

Photos courtesy of Jim Warner


• 1957: First reported use of CompactionGrouting to densify soil.

• Accidental discovery during settlementremediation of swimming pool.

• Pool enclosed within building, no access forlarge equipment.

• Pool built on clay fill.• Fill became saturated through cracks in poolshell.

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Jim Warner’s “Pool Disaster” 1957• Pool constructed in an abandoned

and backfilled basement.• Grout holes were spaced at 4 feet.• Grout injections only intended for

“mudjacking”.• Project seemed a “Disaster” for the

contractor (Warner).• Grout injection at the shallow end

caused dirty water to flow throughdrilled holes in the deep end.

• Water removed in buckets anddisposed of in local catch basin.

• 10 times more grout consumedthan calculated.

• Everyone involved was obviouslyupset, with one exception…

The Soils Engineer

“You have squeezed water out of the fill Thatshouldn’t be possible. It’s WONDERFUL !”

Thus began extensive research & development.


Compaction Grouting – Early Research

• 1969: First use of term “CompactionGrouting” in a journal article by Ed Graf“Compaction Grouting Technique &Observations”, ASCE)– Described use of Koehring Mudjack– Operators pumped “zero slump” grout for raisingstructures

– Quantities > calculated used => soil compaction– Described procedure and basic concepts of CG

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Compaction Grouting – Early Research• 1973: Doug Brown & Jim Warner publish “Compaction

Grouting” in the Journal of Soil Mechanics and FoundationDivision 99(8).– Documents over 10 years of practitioner research.– GC as a soil improvement process.– Importance of grout material.– Importance of injection pressure and rate.– Early modeling of grout inclusion.

• 1974: Warner & Brown “Planning and PerformingCompaction Grouting” Journal of Soil Mechanics andFoundation Division 100(6).


Test excavation toexhume compactiongrout inclusions


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• Good groutrheology

• Coherentgroutinclusions


• Poor groutrheology

• Hydrofracture

Photo courtesy of Daniel Hourihan

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Recognition thatrheology iscontrolled byfine aggregategradation.

Brown & Warner (1973)

Compaction Grouting Research• 1983: Baker, Cording & McPherson, “Compaction Grouting to Control

Ground Movements during Tunneling”, Underground Space

• 1989: Berry & Grive, “Compaction Grouting as an Aid to Construction”,Foundation Engineering Proceedings

• 1992: Graf, “Compaction Grout, 1992”, Grouting, Soil Improvement andGeosynthetics

• 1997: Bandimere, “Compaction Grouting State of Practice – 1997”,Grouting: Compaction, Remediation, Testing

• 2000: Byle “An approach to the design of LMD grouting”, Advances inGrouting and Ground Modification

• 2000: Shuttle & Jefferies, “Prediction and Validation of Compaction GroutEffectiveness”, Advances in Grouting and Ground Modification

• Many more listed in the “References” section of the Consensus Guide

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Mechanics of Compaction Grouting

Compaction Grouting:• Injection of stiff, mortar like grout into theground to displace and compact thesurrounding soil.

• Grout displaces soil during injection and forcessoil particles into tighter packing.

• Air and water are expelled => Reduced porevolume.


• Injected grout material does not hydrofractureor permeate the surrounding soil, providingthe Compaction Grouting process is executedin a controlled fashion.

• This behavior enables consistent densificationaround the expanding grout mass.

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• Compaction Grouting is a strain controlledprocess.

• Injection rate and volume are controlled.

• Injection pressure ismeasured to determinethe ground’s resistance to grout injection.

CG Mechanics – Injection Rate

• Typical injection rate is on the order of 2ft3/min.

• Rule of thumb, 8 psi/min; 1 to 2 ft3/min.

• Slower rates may be needed for sensitiveapplications.

• Higher rates may be used under certainconditions.

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CG Mechanics – Confinement• Soil densification more effective if confinedby stiffer soil zones, either above or adjacentto the expanding grout mass.

• Importance of drilling/injecting to createconfinement.

• Confinement above is related to staging.

Compaction Grouting Mechanics• Grout exits base of casing and

begins to push on surroundingsoil.

• Grout compacts weak soil bypressure displacement.

• Continued grout injection untilone of several terminal criteriaare met:

– High Pressure Exceeded– Surface Uplift Observed– Structure Movement Observed– Surface Cracks Open/Close– Grout Returns to Surface (Rare)– Unexpected Pressure / Volume

Behavior

Injection Rate:

~2 ft^3 / min

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Mechanics of Surface Uplift

• Lateral soil displacement will continue until the grouting force > overburden• Conical soil fracture typical• Dominant vertical displacement w/ shear along conical fracture• Measured surface uplift (0.05 to 0.1 inch) signals end of stage (and practical limit of further

compaction).

Compaction Grouting Mechanics• Grouting performed in

“Stages”, usually from thebottom up.

• Each stage is pumped untilterminal criterion is met.

• Casing is withdrawn inregular intervals assuccessive stages arepumped.

• Result is a relativelyuniform column of treatedsoil.

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Exhumed Grout Column

• Grout remains relativelyconfined in very densesoils or bedrock

• Grout will impart avolumetric strain todisplaced weaker soils,affecting compaction “insitu”

• Result is increaseddensity and uniformity ofthe treated soil profile

Exhumed Grout Column

Same grout column – Grout has displaced weaker soils higher in thetreated profile. Surrounding soils have become denser, and higherstrength grout occupies the resulting void space.

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Compaction Grouting as a Sustainable Practice

• Materials

• Methods

• Applications

CG Sustainable Aspects Materials

Grout strength is not critical (imparts energy & occupiesspace), therefore cement is not a required component ofCG.

CO2 intensity for cement: ~0.9 t per t cement produced(Hanle, 2004, US EPA)

Alternate sources of fine aggregate:• “Reject Sand” from AC batch plants• Bottom Ash has favorable grain size distribution properties,

although coal ash products have recently been the subjectof some controversy…

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CG Sustainable Aspects

Particle Size Distribution: Coal Bottom Ash

Figure after Kim, Prezzi & Salgado, (2005)

GradationEnvelope forCG Aggregate

CG Sustainable Aspects – Methods/Practices

• Use of relatively small scale equipment• Use of current tier compression engines• Efficient transfer of energy to ground• Site surface disturbance is minimal• Relatively little waste or spoil is generated• Use of “Bio lubricants” becoming popular• Real time data acquisition to improve efficiency

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CG Sustainable Aspects Applications

Mitigate liquefaction potentialRaise and relevel settled structuresTreat weak, compressible soilsImprove pile capacityCompact utility trench backfillCompensation for soil loss due to piping or dissolution(sinkholes/Karst)

Inherent ability to work in and around existingstructures with minimal disturbance

Settlement Mitigation of Taxiway at LAX With CG

Equipment removed From TYY after each night shift.

Impact on airport operations was minimal.

CG sufficiently restored bearing condition, avoiding costly demolition andreconstruction.

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Puget Sound Naval Shipyard Bremerton, WA

• Dry Dock #6 originally constructed in1960’s. Largest DD on West Coast

• Increasingly heavier loads required overthe years since initial construction (AircraftCarriers became larger).

• ~ 5” differential settlement

• CG was used to treat a large portion of thefacility’s supporting soils in situ.

• Automated data acquisition / real timemonitoring

• Life of facility was substantially extended,saving countless tax $’s)

Summary• CG is amechanical process for groundimprovement, developed in the mid 20thcentury.

• CG is a strain controlled process (rate iscontrolled, pressure is measured).

• Adequate confinement pressure is needed forsuccessful execution of CG.

• Inherent to the CG process are manysustainable aspects.

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Thank you for your kind attention

The Presenters for the Compaction Grouting Consensus Guide Short Course, their employers, affiliates,successors, and anyone acting under their authority disclaim any and all liability for any personal injury, propertydamage, financial loss, or other damages of any nature whatsoever, including without limitation any direct,indirect, special, exemplary, or consequential damages, resulting from any person’s use of, or reliance on any andall materials presented at the aforesaid short course, which is presented for information purposes only.