Geotechnical Aspects of the Twin Ports Interchange (TPI) Duluth, - - PowerPoint PPT Presentation

Geotechnical Aspects of the Twin Ports Interchange (TPI) Duluth, Minnesota

Rich Lamb, P.E. 2019 Midwest Geotechnical Engineering Conference September 16-19, Columbus, OH

mndot.gov

Sorry, Wisconsin

Project Location

Lake Superior Duluth, Minnesota Superior, Wisconsin Port of Duluth-Superior 1 3 2

Current Interchange

• Known locally as the “Can of Worms”
• 3rd highest crash rate statewide for

interchanges

• 33 aging bridges (built in late ‘60’s),

mainline interstate on land bridge

• 16 bridges weight restricted 7 non-

redundant

• Problem for over-sized and over-weight

traffic coming from port and getting on Interstate

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Routes of Diverted OSOW Traffic

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Current Main Interchange

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I535 Lake Superior Historic Neighborhood

Trestle Bridges (mainline I35 and all ramps)

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US53

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Garfield Interchange I535

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Twin Ports Interchange (TPI) Project Goals

• Enhance safety by eliminating blind merges and

left exits

• Replace aging infrastructure
• Reduce maintenance and closures
• Reduce bridge structure
• Improve freight mobility
• Allow oversize/overweight freight on the Interstate

by reconstruct/rehab substandard bridges

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Project Overview

• Alternate Deliver Method - Construction

Manager/General Contractor (CMGC)

• Currently nearing 60% design status
• Consultant design for both roadway and bridges
• Construction scheduled for 2020-2022 ($250-

300M)

• Driven Pile Load testing and Column Test

Project (Rigid Inclusions) currently underway

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Construction Manager/General Contractor (CMGC)

• Contractor hired at start of design under

professional/technical consultant contract

• Contractor responsibilities
• Constructability Reviews
• Maintenance of Traffic, Construction Staging

Reviews

• Work will be let in two Work Packages
• Three cost estimates (EE, Contractor, ICE) must

be close for Contractor to do work

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Current Design Layout

• 14 New Bridges, 4 Bridge Rehabs
• ~600,000 sq. ft. of Column

Supported Embankments

• Fill heights up to 38 ft.
• 40% reduction in bridge deck area
• 8,000 L.F. Retaining Walls
• Cast-in-Place Concrete Cantilever
• MSE

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Geotechnical Design Team

• Subsurface Investigations, Ret Wall

Geotechnical Reports, Roadway Soils

• Ground Improvement Design, Modeling
• Supplemental Subsurface Investigations
• Early work on TH 53 Embankments
• Lateral Pile Stability

mndot.gov/

Column Supported Embankment Design

• Designed by consultants (Barr

Engineering and Itasca Engineering)

• Most economical column is full

displacement grouted column

• Diameters 16-18 in.
• Column Spacing 8-10 ft.
• Rough Unit Cost ~ $40/sq. ft.
• Includes wall cost

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Subsurface Investigations

• 120 Historic Borings from 1960’s (poorly located, ±50 ft.)
• 150 Cone Penetration Test (CPT) soundings
• 250 Modern SPT Foundation Borings
• Dozen or so Test Pits

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General Subsurface Conditions

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Main Intersection US 53 Garfield Interchange

Very Dense Sand >150 ft. Bedrock Dense Sand Org Silty Clay Sand fill Bedrock

Vert Dense Sand/Silt

Clay

Stiff Silt and Clay

Sand fill Dense Sand

40-60 ft 100 ft. 150 ft. 10-55 ft. thick

Clay

Var.

Soil Variability

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Soil Variability

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107 ft. 54 ft. 41 ft. Miller Creek Culvert Inlet Bridge 69902 West Abut 35 ft.

Sloping Bedrock

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90 ft. 500 ft. Bedrock Miller/Coffee Creek Culvet

3D Soil Model

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High Ground Water Table

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Lake Superior 603.5 MSL Existing Grade ~606

Lake Tides

• Strong North Wind = 1-2 “tide”

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Soil Contamination

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Soil Contamination

• Petroleum, lead, arsenic, PAH, Asbestos

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Big Geotechnical Challenges

• Avoiding any excavation to limit cost of treating

contaminated soil and groundwater

• Possible Steel Corrosion from contaminated soil
• Construction Staging does not allow for

embankment settlement wait periods

• High groundwater
• Urban fill

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Bigger Geotechnical Challenges

• Interaction of CSE foundation elements with

bridge/wall driven piles

• Ground heave/lateral displacement from

“forest” of full displacement columns

• Low fill ground improvement
• Building bridge/walls/embankments over in-

place utilities

• Reviewing designs using finite difference

method

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Low Embankments

• No excavation
• No settlement wait periods
• 1 inch of long term

allowable settlement

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4-6 ft. fill Weak Soils, highly contaminated 30-60 ft. Dense Soils

Low Embankment Foundation Design

• Columns Supported

Embankment

• Driven piles or grouted

columns

• 10 ft. center spacing
• 1 ft. thick reinforced

concrete LTP

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LTP Dense Soils 4-6 ft. fill

Interaction of CSE columns and bridge piles

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Ground Heave/Lateral Displacement Problem

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Driven Piles Full Displacement Columns

Column Test Project

• 63 CMC

column 18

• in. dia. 65 ft.
• Wick drains

½ area

• Driven 16 in.

pipe pile

• Two Static

Load Tests

• n columns
• Instruments

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Column Test Layout

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Test Area Soils

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65 ft.

Column Test Embankment

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Instrumentation

• 63 total gages
• Piezometers
• Survey targets
• Extensometers
• ShapeAccelArray
• Vertical and horizontal
• Strain Gages

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Initial Instrumentation Results

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Current Instrumentation Results

• Lateral Deflections ~4 inches near columns (3 ft), but only

½ inch 10 ft. away

• Heave – 1 inch
• Pore Pressures – dissipates quickly

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Vertical SAA

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If Ground Movement is Problem

• Use non-displacement columns or H pile

in “buffer zones”

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Auger Cast

• r H Pile

Full Displacement Columns

1 2

3

Sanitary Lift Station

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Cross Section

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Options

• Remove building
• Fill-in basement and drill

foundations through floor

• Span over

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Bridge Piling Adjustments

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Reviewing CSE Designs

• How to check 2d, 2.5d and 3d Finite Difference

Method models

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Thank you

Rich Lamb

rich.lamb@state.mn.us 651-366-5595

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Column Supported Embankments 101

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Embankment Load Transfer Platform Weak Soils Dense Soils Rigid Inclusions (columns/piles)

(70-95% of embankment load)

Rigid Inclusions (Columns or Piles)

• Full Displacement Grout Columns
• Non-displacement Grout Columns
• Driven piles
• H sections
• Pipe sections
• Typical Spacing 5-10 ft. centers
• Pile Caps typically used

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$12-$20 / LF $30-$40 / LF

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CSE with misc Structures/Utilities

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Embankment MSE Wall CIP Wall Storm Sewer

Exit 535 EB

OH Sign Light Tower

Archaeological Concerns

• I-535 and Garfield Avenue
• Brown’s Trading Post
• North side of Piedmont Avenue
• Known Native Cemetery
• Some graves relocated in 1870 to Railyard
• Coffee Creek Banks
• Culvert built over stream and filled
• Beneath the structure
• Old Lakeshore
• Drilling in these areas suspended

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Load Transfer Platform Design

• Acts as a pile cap – evenly distributes load to columns
• Select well graded granular fill (94-98% compaction) (MnDOT Class 5)
• Minimum of three horizontal biaxial geosynthetic reinforcement

layers with vertical spacing of 8-18 in.

• LTP thickness (½ the clear span between columns)

Full Displacement Columns

• “Drilled Displacement Piles”
• Very few spoils, low noise, vibration
• Reverse flight Augers push soils down

and away from column

• May displace soils laterally – problem

for adjacent structures

• Diameters of 12-24 inches, and

typical lengths of 65-85 ft.

• Difficult to penetrate dense soil

layers

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Menard – Controlled Modulus Column

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Non Displacement Columns

• “Auger Cast Pile” or

“Continuous Flight Auger Pile”

• Diameters of 12-24 in.
• Depths of 100 ft. or more
• Low noise, vibration
• Spoils much greater than FDC

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Displacement Piles

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Non-Displacement Piles

• “Pile Supported Embankment”

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Questions or Comments?

Geology

• What has shaped the subsurface conditions the project

site?

• Volcanoes (igneous bedrock)
• Glaciers (dense soils)
• Lake Sediments (organics and soft clay)
• Erosion from stream flow (variability)
• Land use (surface fill material, contaminants)

mndot.gov/

Subsurface Investigations

• 120 Historical Borings (1960s)

(bridges)

• 100 Modern Borings (AET)

(bridges)

• 150 Cone Penetration Test

(CPT) Soundings (embankments)

• 150 Future holes

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75-100’

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Tall Embankments

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Embankment 20-40 ft. Weak Soils 30-60 ft. Dense Soils

Tall Embankments

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Embankment 20-40 ft. Weak Soils 30-60 ft. Dense Soils

Typical Section I35 and Ramps

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Org Chart - CMGC

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Typical Section for CSE

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Typical Section for CSE

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Perched Abutments

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Weak Soils, highly contaminated 30-60 ft. MSE Wall Dense Soils

Main Interchange

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US 53 Bridges

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Garfield Interchange

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