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Case Study: Rapid Embankment Construction of US 17 Bypass Interchange Over Soft Compressible Soils

Using Lightweight Aggregate Myrtle Beach, South Carolina

Ed Tavera, PE Jeff Speck, PE

February 17 - 20, 2013

Presented By:

Louisiana Transportation Conference

Big River Industries, Inc.

• Project Overview & Design Requirements

• Project Constraints

• Geotechnical Challenges

• Rapid Embankment Construction

• Lightweight Aggregate Borrow Proposed

• Compaction Verification

• Lightweight Aggregate Supply & Delivery

• Automated Geotechnical Instrumentation & Results

• Project Construction Pictures

• Closing

Presentation Agenda

PROJECT OVERVIEW

Project Location Myrtle Beach, SC

Project Location

Project Site

US17 Bypass

East

N. Myrtle Beach Murrels Inlet

SC 707

• Relieve growing traffic congestion

• Provide a facility to handle future development and growth

• Construct a safe, signature project for the stakeholders (Horry County, SC)

Purpose

US 17 Bypass

Farrow Parkway

SC 707

Ramp C

Ramp A

Ramp D

Ramp B

Project Layout

Proposed Interchange

175’ 225’ 300’ 175’ 140’ 225’

Bridge Span Lengths (Bridge Length 1,240 Feet)

Bridge Aesthetic Features

Bridge Features Interior Bent Cap Extensions

Retaining Wall Features (Rendering)

Wall Features

Columbia International Airport Interchange

• Local Funding - led to higher expectations for project completion

• Heavy traffic volumes necessitated accelerated construction

• Elimination of long settlement waiting period

– Led to innovative geotechnical design and construct techniques

Schedule

DESIGN REQUIREMENTS

AASHTO LRFD Design • Strength Limit State • Service Limit State • Extreme Event I Limit State (Seismic) • Extreme Event II Limit State (Collision)

Design Requirements

Performance Based Design

• Service Limit State

• Extreme Event I Limit State (Seismic)

• Extreme Event II Limit State (Collision)

AASHTO LRFD Design • Strength Limit State • Service Limit State • Extreme Event I Limit State (Seismic) • Extreme Event II Limit State (Collision)

Performance Based Design

• Service Limit State

• Extreme Event I Limit State (Seismic)

• Extreme Event II Limit State (Collision)

US Earthquakes 1705 - 1996 Seismic Hazard

1886 Charleston Earthquake

MW 7.3

• Charleston fault zone (“Woodstock” fault) and the “Zone of River Anomalies” (ZRA) fault source

• Moment magnitude from 7.0 to 7.5.

• 1886 Charleston Earthquake

SC Seismic Hazard

SC Seismic Hazard

FEE PGA 0.06g @ B/C Boundary

SEE PGA 0.24g @ B/C Boundary

• Safety Evaluation Earthquake (SEE), ground shaking having a 3% probability of exceedance in 75 years (2,500 year return period) PGA = 0.39g

• Functional Evaluation Earthquake (FEE), ground shaking having a 15% probability of exceedance in 75 years (500 year return period) PGA = 0.13g

Extreme Event I Limit State SC Design Earthquakes

PROJECT CONSTRAINTS

• High existing traffic volume

• No lane closures during summer months

• Maintaining access to numerous businesses

Traffic Control

• Complex construction traffic control plan • 8 proposed stages of construction • Maintain existing number of lanes • Temporary pavement • Multiple traffic shifts • Temporary alignments • Detour routes

• Traffic Control – Maintain Existing Number of Lanes & Access to Numerous Business

• Embankment Construction – Traffic Control Stages 2, 3, and 4

• Project Geometry and Layout

– Existing Alignment

– Limited R/W

• Limited Construction Staging Areas

• Construction Time Requirements – 3.5 years

Project Constraints

GEOTECHNICAL CHALLENGES

Fantasy Harbour

US 17/SC 707 (Backgate)

2 Miles Away!

Myrtle Beach, SC Regional Experience

• 2 Miles North of US 17 /SC 707 Interchange

• New Alignment

• Bridge Over the Atlantic Intracoastal Waterway

• 3.1 Miles Roadway Approaches and Bridge

Fantasy Harbour

Fantasy Harbour West Abutment Subsurface Soils

SB2 RB-24 RB-25 RB-27 SB1 RB-28 RB-29

0 ft-msl

-50 ft-msl

Pee Dee Formation

Very soft to medium CLAYs (CL/CH)

Very loose to medium SANDs (SP/SC/SM)

Fantasy Harbour East Abutment Subsurface Soils

RB-13 SB6 SB1 RB-11 RB-16 SB2-A

SB3-A

SB5

0 ft-msl

-50 ft-msl

Very loose to medium SANDS (SP/SM/SC

Pee Dee Formation

Very soft to medium CLAYs (CL/CH)

• 10’ – 42’ Embankment, Settlement 9” to 67”

• Liquefaction – Loose Sands • Embankment Slope

Instability (Static/Seismic)

Fantasy Harbour Geotechnical Experience

• Ground Improvement!!! • 2 Year Embankment Construction Contract • 2-3 Year Bridge Construction Contract

North Bridge Approach

South Bridge Approach

Let’s Return To US 17/ SC707 Interchange (Backgate)

South Bridge Approach Subsurface General Profile

North Bridge Approach Subsurface General Profile

• 30’ to 60’ - Soft to Firm Clay

• Pockets of Loose Sands in upper 10’

• Intermediate Medium Sands (253+00 to 256+00)

• Loose Sands above Dense Sands (Liquefiable)

• Pee Dee Formation

Geotechnical Challenges

Bridge Abutment Settlement (Normal Weight Fill 120 pcf)

• Poor Site Subgrade (2’ – 3’ Bridging Required)

• Excessive Settlement – (Total & Differential)

• Static Slope Embankment Instability/Bearing

• Seismic Slope Embankment Instability (Liquefaction)

Geotechnical Challenges

RAPID EMBANKMENT CONSTRUCTION

Geotechnical Challenges

Project Constraints

Rapid Embankment Construction

• Settlement – Total & Differential

• Embankment Slope Instability / Bearing (Static/Seismic)

• Bridge Abutment Foundation Performance - Extreme Event I and II Limit States

• MSE Wall Construction Over Soft Soils

Geotechnical Key Design Issues

• Lightweight Aggregate Borrow – Reduce Magnitude of Settlement

• Prefabricated Vertical Drain (PVD) / Granular Surcharges – Increase Rate of Settlement and Facilitate Rapid Construction

• Deep Soil Mixing – Improve Seismic Slope Stability and Bridge Abutment Foundation Performance

• Mechanically Stabilized Earth (MSE) Walls

2-Stage and 3-Stage MSE Wall Construction

Vertical Slip Joints

Geotechnical Design Approach

Granular Surcharge Properties: • = 32 degrees • Unit Weight: 125 pcf

Granular Surcharge

Lightweight Aggregate

Borrow Material

Lightweight Aggregate Properties: • = 40 degrees • Short Term Unit Weight: 60 pcf • Long Term Unit Weight: 70 pcf • MSE Wall Backfill Properties

½ Normal Weight

Normal Weight

Lightweight Aggregate

Granular Surcharge & Lightweight Aggregate Borrow

Lightweight Aggregate Borrow (Rotary Kiln Produced)

226,000 CY

3 Million LF

PVD Installation

PVD

PVD Triangular Installation Pattern

PVD

S

2’ Drainage Sand Layer

Geotextile Separator Fabric

s = 3’ and 4’

PVD Installation

Predrilling PVD Installation 309,000 LF

PVD Installation Obstructions!!!

Permanent MSE Walls • Two-Stage Construction • Three-Stage Construction (w/Drainage Structures)

Temporary MSE Walls (Welded Wire Mesh Facing)

30,500 SF

51,500 SF

MSE Walls

• Seismic Slope Stabilization – Shear Key • Improved Performance of Bridge Abutment Foundations • 2013

35,600 CY

Deep Soil Mixing Columns (Overlap – Block Pattern)

Bridge Abutment DSM Longitudinal DSM Longitudinal DSM

Deep Soil Mixing Columns (Overlap – Block Pattern)

Legend

Test Lime-Cement Columns (Test LCC)

DSM-LCC Test Section 1

(Block Type Pattern)

DSM-LCC Test Section 2

(Single Line Pattern)

10 Feet Min.

10

Fe

et M

in.

Test LCC No. 1 2 3 4

Test Pile 1 (HP 14x117)

Test LCC Sampling Quadrants

1

2

4

3

Deep Soil Mixing Test Sections

CONSTRUCTION SEQUENCE

Ramp B Stage 2

Ramp D Stage 3

Bridge Approach Embankment Stage 4

Project Construction Stages (North Abutment 252+01)

Bridge Abutment Construction (North Abutment – End Bent 7)

HP 14x117 22 Piles/row

30 Feet

DSM-LCC Block Type Pattern MSE Wall Leveling Pad

PVD (Wick Drains)

MSE Wall Concrete Panel Facing

Bridge Wing Wall Vertical Slip Joints

Bridge Abutment Construction

LIGHTWEIGHT AGGREGATE

BORROW PROPOSED

Lightweight Aggregate Borrow (Proposed New Material)

Lightweight Aggregate Borrow (Rotary Kiln Produced)

0

10

20

30

40

50

60

70

80

90

100

0.0100.1001.00010.000100.0001000.000

% P

assi

ng

Grain Size (mm)

LWF Min

LWF Max

713 Min

713 Max

BR Min

BR Max

LWA (S15922)

Section 713 MSE Wall

Big River Proposed Lightweight Aggregate

1 ½" ¾" 3/8" # 4 # 100 # 40 # 30 # 200

Grain Size Curve

Lightweight Aggregate Borrow Soil Properties (Item 2033020)

Soil Properties SCDOT Specified Proposed

Minimum: Dry Unit Weight, gDry (pcf) 55 43*

Maximum: Dry Unit Weight, gDry (pcf) 60 45**

Minimum: Wet Unit Weight, gWet (pcf) 60 55**

Maximum: Wet Unit Weight, gWet (pcf) 70 60**

* 95% Maximum Density **Estimated based on laboratory testing submitted by Big River Industries

Lightweight Aggregate Density Properties

• Higher Fines Content

• Lower Dry Unit Weight

• Total Unit Weight 15% Less Than Designed

• High Absorption

• Gradation – Coarse Sand Vs. Aggregate

• Compaction Verification Required by SCDOT

Lightweight Aggregate Borrow (Proposed New Material Differences)

Test Section #1 (Dry)

Test Section #1 (Wet)

Granular Surcharge

Granular Backfill

Lightweight Aggregate

Borrow Material

• Design Team Performed a Redesign

• Reduced the Lightweight Quantity by 15%

• Saved Horry County $2 Million

Granular Surcharge & Lightweight Aggregate Borrow

COMPACTION VERIFICATION

Interparticle Moisture

Interparticle Voids

Particle Absorbed Moisture

Particle Pore Voids

Particle Ceramic Solids

Lightweight Aggregate Borrow Compaction Verification Challenges

• Laboratory Compaction Curves

• Target 95% Max Dry Density = 43 pcf

• Moisture Content Varied Significantly for the same Dry Density

Compaction Control

• Test Section #2 - Evaluate Compaction Control Methods

• Compaction Control - 1 Cu. Ft. Steel Box, Calibrated Nuclear Density Gauge, Sand Cone, and EDG.

Test Section #2 Compaction Control

SC = Sand Cone NG = Nuclear Gauge EDG = Electric Density Gauge STB = Steel Test Box

EDG-1

Compacted Lightweight Aggregate

Borrow MC-3

STB

EDG-2 SC-1

SC-2

SC-3

MC = Hot Plate & Oven Moisture Content MT = Moisture Tester MTB = Moisture Tester in Steel Box

MC-1 MC-2

EDG-3

NG-1

NG-2

NG-3

MT-1

MT-2

MT-3 MT-4

MTB-1 MT-5 MT-6

MT-7 MT-8 MTB-2

MTB-3

Test Section #2 Field Testing Set

Test Section #2 1 Cu. Ft Steel Box (Control Test)

Test

Set Moisture Added Process Compaction Effort

1 As delivered Compact 3 passes with vibratory roller

2 No Water Added Scarify & Compact 4 passes with a vibratory roller

3

Added Water - 1 Pass Scarify & Compact 8 passes with a walk behind

vibratory flat plate compactor

4 Added Water - 2 Passes Scarify & Compact 3 passes with a vibratory roller

5 No Water Added Scarify & Compact 4 passes with a vibratory roller

6 No Water Added Scarify & Compact 8 passes with a vibratory roller

7

Added Water- 2.5 Passes

(Saturated) Scarify & Compact

3 passes with a vibratory roller

Test Section #2 Field Testing Sets

Test Section #2

Compaction Control Calibrated Nuclear Gauge

LIGHTWEIGHT AGGREGATE

SUPPLY & DELIVERY

Big River Industries Livingston, AL – Myrtle Beach, SC

Big River Industries 500 Mile Radius – Livingston, AL

Livlite Big River Industries

Lightweight Aggregate Borrow Pre-conditioning

Lightweight Aggregate Borrow Pre-conditioning

CONSTRAINTS

Ramp B Construction Pre-conditioned Lightweight Aggregate

CONSTRAINTS

Ramp B Construction Pre-conditioned Lightweight Aggregate

GEOTECHNICAL INSTRUMENTATION

Settlement Monitoring • 4 Magnetic Extensometer • 10 Settlement Plates • 12 VW Settlement Sensors • 17 VW Piezometers • 2 VW Data Collection Centers

Slope Stability • 6 Slope Inclinometers

Geotechnical Instrumentation

Spider Magnet Pre-Assembled ME Telescoping Section

VW Magnetic Extensometers

-70

-60

-50

-40

-30

-20

-10

0

10

20

-10.0-9.0-8.0-7.0-6.0-5.0-4.0-3.0-2.0-1.00.01.0

Ele

vati

on

(fe

et)

Settlement (Inches)

12/1/2011

12/7/2011

12/14/2011

12/19/2011

12/21/2011

12/27/2011

12/29/2011

1/4/2012

1/12/2012

1/18/2012

1/25/2012

2/1/2012

12-22-2011 Embankment Construction

Finished

-8

-7

-6

-5

-4

-3

-2

-1

0

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9

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12

0 7 14 21 28 35 42 49 56 63 70

Emb

ankm

en

t H

eig

ht

(Fe

et)

Days

EmbankmentHeightTop of LWF

Datum Magnet

SA-1

SA-2

Sett

lem

en

t (I

nch

es)

Instrumentation Results ME Extensometers

VW Piezometers

Instrumentation Results VW Piezometers

Settlement Plates

VW Settlement Sensors

VW Settlement Sensor Data Collection

VW Data Collection

Logger

VW Settlement

Sensors

VW Piezometers Engineer

Internet

Power Source (Solar Power)

Database Server

Cellular Phone

VW Device Connection

Board

VW Data Collection Center

Automated Data Collection

VW Devices connected to 16-channel Board

VW Device Connections

iSite Logger with Solar Controller Charging Battery

Inside DCC Enclosure & Solar Panel

Data Collection Center

X-Section End Bent 1 (South Bridge Abutment, 237+50)

Ramp A

Settlement Transverse Profile (South Bridge Abutment – 237+83)

Ramp A Settlement Measurements

2-12-2011 Embankment Construction

Finished

2-14-2012 Surcharge Removed

-6

-5

-4

-3

-2

-1

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84

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Emb

ankm

en

t H

eigh

t (F

eet)

Days Since VWSS Installed

US-17 Bypass Settlement Sensor A-VWSS-2

Embankment Height

Lightweight Fill Height

SS Reading No. 1- 5:00

SS Reading No. 2- 12:00

SS Reading No. 3- 19:00

SS Reading No. 4- 23:00

Sett

lem

en

t

Ramp C

Settlement Transverse Profile (South Bridge Abutment – 237+83)

Ramp C Settlement Measurements

9-13-2012 Emankment Construction Finished

12-14-2012 Surcharge Removed

-3

-2

-1

0

1

2

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Emb

ankm

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t H

eigh

t (F

eet)

Days Since VWSS Installed

Embankment Height

Lightweight Fill Height

SS Reading No. 1- 5:00

SS Reading No. 2-11:00

Sett

lem

en

t (I

nch

es)

X-Section End Bent 7 (North Bridge Abutment, 250+26)

Ramp B

Settlement Transverse Profile (North Bridge Abutment - 250+26)

12-22-2011 Embankment Construction

Finished

4-10-2012 Surcharge Removal

-12

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Emb

ankm

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eigh

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eet)

Days Since VWSS Installed

Settlement Sensor

Embankment Height

Lightweight Fill Height

SS Reading No. 1 - 5:0:0

SS Reading No. 2 - 12:0:0

SS Reading No. 3 - 19:0:0

SS Reading No. 4 - 23:0:0

Sett

lem

en

t

Ramp B Settlement Measurements

Ramp D

Settlement Transverse Profile (North Bridge Abutment - 250+26)

Ramp D Settlement Measurements

10-26-2012 Emankment

Construction Finished

2-5-2013 Surcharge Removed

-14-13-12-11-10

-9-8-7-6-5-4-3-2-10123456789

101112131415161718192021222324

0 14 28 42 56 70 84 98 112 126 140 154 168 182

Emb

ankm

en

t H

eigh

t (F

eet)

Days Since VWSS Installed

EmbankmentHeightLightweight FillHeightSS Reading No. 1-5:00SS Reading No. 2-12:00SS Reading No. 3-19:00

Sett

lem

en

t

PROJECT CONSTRUCTION

• MSE Walls • Lightweight Aggregate Borrow Material • 2’, and 3’ Granular Surcharge (Normal Weight) • 3’ and 4’ Triangular Spacing PVD • Geotechnical Instrumentation

Ramp B Ramp A

Traffic Control Stage 2

Traffic Control Stage 2

Ramp A Construction

US 17 Bypass NB

Traffic Control Stage 2

Ramp B Construction

US 17 Bypass NB

Construction Ramp A & B (PVD Installation)

Construction Ramp A & B (PVD Installation)

Construction Ramp A & B (MSE Wall Embankment Construction)

Construction Ramp A & B (MSE Wall Embankment Construction)

2 Feet Thick Cover of Borrow Silty or Clayey Soil Materials

Lightweight Aggregate Borrow Material

4 Feet Long Biaxial Geogrids Placed on 2 Feet Vertical Spacing

Sloped Lightweight Aggregate Embankment

Sloped Lightweight Aggregate Embankment

Ramp C Ramp D

• MSE Walls • Lightweight Aggregate Borrow Material • 1’, 2’, and 4’ Granular Surcharge (Normal Weight) • 3’ and 4’ Triangular Spacing PVD • Geotechnical Instrumentation

Traffic Control Stage 3

Constructed Ramps A/B (Completed – Stage 2)

Existing NB = Stage 3 SB

Ramps C/D Under Construction -Stage 3

Traffic Control Stage 3 (Ramps A & B Completed)

Traffic on Ramp A

Existing NB = Stage 3 SB

Traffic Control Stage 3 (Ramps A & B Completed)

Traffic on Ramp C

Construction Ramp C

US 17 Bypass SB

Traffic on Ramp C

Construction Ramp C

US 17 Bypass SB

Ramp D

Construction Ramp C

US 17 Bypass SB

Traffic on Ramp B

Ramp D

Construction Ramp D

South Bridge Approach North Bridge Approach Backgate Bridge

• MSE Walls • Lightweight Aggregate Borrow Material • 1’, 2’, and 3’ Granular Surcharge (Normal Weight) • 3’ Triangular Spacing PVD • Geotechnical Instrumentation • Bridge Abutment DSM (South 30’ x 133’ x 50’deep – North 30’ x 141’ x 70’deep ) • Longitudinal DSM (South 5’ Wide / North 8’ Wide)

Traffic Control Stage 4

CLOSING

Project Status

• Preliminary Engineering: 2008 - 2009

• Right of Way Acquisition: 2009 - 2011

• Construction: 2011 – 2014

– Approximately 33% complete

Under Construction

• Traffic Stage 3 – Ramps C/D have been constructed and will be ready to be paved in the near future

• Traffic Stage 4 – Scheduled to Start April 2013

– Deep Soil Mixing : Test Section / Test Pile / Production

– Bridge Abutment Foundation Construction

– Construct Bridge Approach Embankment & MSE Walls

• Geotechnical techniques are speeding up construction

• Positive feedback regarding construction traffic congestion and shifts

• Estimated project completion: Fall 2014

• Project Cost $75.8 Million

Closing

Thank You Any Questions?