richards micro pile construction methods and materials

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Micropile ConstructionMethods & Materials

Presented BPresented ByTom Richards, Chief Engineer

Nicholson Construction CompanyNicholson Construction Company12 McClane Street, Cuddy, PA 1503112 McClane Street, Cuddy, PA 15031

Phone: 412.221.4500Phone: 412.221.4500trichards@nicholsonconstruction.comtrichards@nicholsonconstruction.comt c a ds@ c o so co st uct o cot c a ds@ c o so co st uct o co

Including information fromDonald Bruce

GeoSystems, LP

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Soil Drilling Methods(excluding “Open Hole”)

• Single Tube Advancement (External flush)Single Tube Advancement (External flush)• Rotary Duplex• Rotary Percussive Duplex (Concentric)• Rotary Percussive Duplex (Eccentric)• Double Head Duplex• Auger• Auger• Sonic• “Self Drilling”

Slide Courtesy: GeoSystems LP

•Opening larger than casing size

External Flush Drilling

size•Risk of ground loss in cohesionless soils•Good cleaning of borehole•Tremie grouted through casing g g g- then pulled with tremie head or excess pressure - enhances lateral confinement

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Duplex Drilling

•Often specified- less risk•Minimal loss of ground in cohesionless soils•Grouted through the

i h ll dcasing - then pulled with tremie head or excess pressure

Duplex Drill Casing and Roller Bit

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Water Flush thru Duplex Ejector

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Rotary Eccentric Percussive Duplex DrillingWe call it Tubex

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Tubex Setup

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“Self Drilling” Hollow Bars

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Photo Courtesy of Con-Tech Systems, Vancouver, BC

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Rock Drilling Methods

• High Rotational Speed / Low Torque RotaryHigh Rotational Speed / Low Torque Rotary(e.g., coring)

• Low Rotational Speed / High Torque Rotary(e.g., tricone)

• Rotary Percussive• Top HammerTop Hammer• Down-the-hole Hammer

Slide Courtesy: GeoSystems LP

Micropiles – Classification Based on Grouting Method

Type A: Gravity

Type B: Pressureti th h igrouting through casing

Type C: Single, globalpost grout

Type D: Multiple,repeatable post grout

Slide Courtesy: GeoSystems LP & FHWA

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Type B Micropile(Same effect could be achieved through the drill head)

Slide Courtesy: GeoSystems LP

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Materials

St l C i• Steel Casing• Use Mill Secondary Oil Field

Casing• Typically Flush threaded joints• Typically Flush threaded joints • 80 ksi minYield Strength

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Typical Casing Joint

Casing End with Special Shear Rings

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Grooved Oversized Hole in Existing Foundation

Grooving Problems – AnkerBonder Manufacturer out of business

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Grooving Problem SolutionNichBonderdesigned by Tom Fleet with Danny Mirtand built by Tom Fleet, Star Iron, and

Tom JohnsonTom Johnson

Materials

• Grout• Neat Cement with

Water/Cement Ratio of 0.45• Compressive Strength of 4 6 ksi• Compressive Strength of 4-6 ksi

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Materials

• Reinforcing BarsReinforcing Bars• Grade 60• Grade 75• Grade 150• Centralizers are used

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Dywidag THREADBAR

• ASTM 615 & ASTM 722• Sizes #6 through #20 Grade 60 & 75• 5/8”, 7/8”, 1”, 1-1/4, 1-3/8”, 1-3/4”, 2-1/2” GR 150 / 160

Rebar with Centralizer Installation

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Ischebeck / Titan Bar Options MAI Similar

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Quality Control

MATERIALSMATERIALS

Coupon Tests on Casing

Mill Certs on Bars

Grout Cubes - quality batching and mixing

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Equipment

DK 50

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Inside work completed at night

Photo Courtesy: GeoSystems LP

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Photo Courtesy: GeoSystems LP

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C 12

C14 - The only ones in North America!

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Photo Courtesy: GeoSystems LP

Basic Grouting Equipment

• Mixer• Mixer• Agitated hopper• Grout pump• Flow and pressure monitoring system• QC testing facility

Slide Courtesy: GeoSystems LP

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Grout Mixing Equipment

High-speed colloidal mixers are superior to standard slow-speed mechanical mixers

fbecause they produce grout of greater uniformity and with better hydration characteristics.

Slide Courtesy: GeoSystems LP

Grout Pumps

• Various types are available and should be• Various types are available and should be selected based on individual job requirements.

• Either piston pumps or progressive cavity pumps can be used.

• Mainly progressive cavity pumps are used• Mainly progressive cavity pumps are used.

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Photo Courtesy: GeoSystems LP

Photo Courtesy: GeoSystems LP

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REGROUT PUMPS

a.k.a Henderson Pumps

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Grout QC testing

Flow and pressure monitoring system