T11 geophysical testing-landschoot

GEOPHYSICAL TESTING FORSUBSURFACE INVESTIGATIONS

Speakers:Myron Hayden, Ph.D., P.E.

Matthew Monteith, E.I.MARCH 2013

ENVIRONMENTAL AND GEOTECHNICAL SPECIALISTSEngineers and Scientists

PRESENTATION SUMMARY• GEOPHYSICAL TEST METHODS

• ELECTRICAL RESISTIVITY IMAGING (ERI)

WHAT IS ERI ENGINEERING APPLICATIONS OF ERI CASE STUDY: BOCA CHUBA SWMF

• GROUND PENETRATING RADAR (GPR)

WHAT IS GPR ENGINEERING APPLICATIONS OF GPR CASE STUDY: I-10 PAVEMENT SURVEY CASE STUDY: SR 26 (NEWBERRY ROAD) CASE STUDY: SR 10 (US 90) DEPRESSIONS


GEOPHYSICAL TEST METHODS• What is Geophysical Testing?

• “Geophysical Testing uses surface test methods to measure the physical properties and conditions of the subsurface material.”

• Measured Physical Properties:

• Seismic, Gravitational, Magnetic, Electrical, Electromagnetic;

• Geophysical Test Methods performed by EGS:

• Electrical Resistivity Imaging (ERI) – Electrical Properties

• Ground Penetrating Radar (GPR) – Electromagnetic Properties


ELECTRICAL RESISTIVITY IMAGING (ERI)• ERI is a geophysical test method performed from the ground surface and used to

generate 2-dimensional and 3-dimensional models of subsurface conditions.

ERI TEST EQUIPMENT AND DATA RECORDER ERI TRANSECT LINE

TESTING IN PROGRESS!


ENGINEERING APPLICATIONS OF ERI Cavity and Sinkhole Detection Geotechnical Site Characterization Groundwater Exploration Well Drawdown Studies Archaeological Site Investigation Detection of Contaminant Plumes Delineation of Organic Material Detection of Buried Debris Detection of Buried Utilities Underwater Tomography



BOCA CHUBA STORMWATER MANAGEMENT FACILITYCAPITAL CASCADES PARK

TALLAHASSEE / LEON COUNTY, FLORIDA

CASE STUDY:ELECTRICAL RESISTIVITY IMAGING (ERI) SURVEY

BACKGROUND INFORMATION


VIEW OF BOCA CHUBA SWMFVIEW OF RETAINING WALL

CLOSE-UP VIEW OF SIDEWALK SEPARATIONVIEW OF SIDEWALK SEPARATION BEHIND WALL

RESULTS OF ERI SURVEY












GROUND PENETRATING RADAR (GPR)• “GPR is a geophysical test method that transmits high frequency electromagnetic waves into

the ground that are reflected back due to changes in the electromagnetic potential of the subsurface materials.”

• GPR data is used to generate 2-dimensional and 3-dimensional models of subsurface conditions.


GPR SCANNING USING 250 MHz ANTENNA

GPR SCANNING USING 1.6 GHz ANTENNA GPR SCANNING USING 100 MHz ANTENNA

GROUND PENETRATING RADAR (GPR)

• Data collection occurs continuously and is displayed on a “real-time” display. This allows for preliminary field interpretation of results which is beneficial for time sensitive projects.


GPR SCANNING USING 250 MHz ANTENNA 2-D GPR PROFILE OBSERVED IN THE FIELDHOW GPR WORKS

ENGINEERING APPLICATIONS OF GPR

• Void Detection• Pavement Composition and Thickness• Utility Locations• Geotechnical Site Characterization• Karst Investigations• Detection of Buried Debris and Structures• Mapping Steel Reinforcement in Concrete• Unmarked Grave Locations



I-10 FROM WEST OF SR 95 TO EAST OF CR 95ARESURFACE, RESTORATION AND REHABILITATION

ESCAMBIA COUNTY, FLORIDA

CASE STUDY:GPR PAVEMENT SURVEY

PROJECT DESCRIPTION• Restoration, Rehabilitation, and Resurfacing of Major

Interchange along I-10

Mainline Roadway I-10

On and Off Ramps

• Determine Existing Pavement Characteristics;

Thickness and Layer Type

Asphalt, Base, Subgrade, and Embankment Materials

• Design New Pavement Section


MAINLINE ROADWAY I-10

PROJECT AERIAL VIEW


PROJECT CONCERNS• Field Safety during Pavement Coring

Poor Vertical Sight Distance

Poor Horizontal Sight Distance

Unsafe Lane Closure Conditions

Required Extensive MOT

Traffic Delays

• Unable to Core Single Lane Ramps


MAINLINE ROADWAY I-10

SINGLE LANE ON-RAMP TO I-10

GPR PROJECT APPROACH• Reduce the Quantity of Pavement Cores

• Conduct a GPR Survey to Determine Pavement Conditions

Three (3) Scans / Travel Lane

Scan at Highway Speeds

Highly Accurate GPS collecting location data

• BENEFIT:

Reduced Lane Closures – Improved Worker and Motorist Safety

Reduced Traffic Delays

Collection of Pavement Data Where It Was Not Possible To Core

Continuous Pavement Data


GPR SURVEY EQUIPMENT


GPR DATA


GPR DATA


GPR BENEFITS

• Identified Locations of Concrete Pavement

Reduced Damage to Milling Equipment

• Identified Pavement Characteristics at On and Off Ramps

• GPR Survey Conducted at Highway Speeds



SR 26 (NEWBERRY ROAD)RESURFACE, RESTORATION AND REHABILITATION

ALACHUA COUNTY, FLORIDA

CASE STUDY:GPR PAVEMENT SURVEY

PROJECT DESCRIPTION• Restoration, Rehabilitation, and Resurfacing of Major Roadway

• EGS’ ROLE:

Identify Cause(s) of Distress

Prepare Remediation Recommendations


MAINLINE ROADWAY SR 26 (NEWBERRY ROAD)MAINLINE ROADWAY SR 26 (NEWBERRY ROAD) DISTRESS

PROJECT AERIAL


END PROJECT

BEGIN PROJECT

AREA 1

AREA 2

GPR SURVEY EQUIPMENT


DISTRESSED AREA 1 GPR DATA


ASPHALT THICKNESS CONTOUR MAP



BASE THICKNESS CONTOUR MAP



ASPHALT THICKNESS CONTOUR MAP



BASE THICKNESS CONTOUR MAP



UTILITY PROFILE


SR 10 (US 90) BRIDGE APPROACH AND ROADWAY DEPRESSIONSRESURFACE, RESTORATION AND REHABILITATION

MADISON COUNTY, FLORIDA

CASE STUDY:GPR SURVEY

PROJECT DESCRIPTION• Restoration, Rehabilitation, and Resurfacing of Major Roadway

• EGS’ ROLE: Investigate Roadway Depressions

Identify Cause of Depressions

Prepare Remediation Recommendations


DEPRESSION AREA IN TRAVEL LANEBRIDGE OVER THE AUCILLA RIVER

PROJECT AERIAL


AREA 1

AREA 2

ROADWAY DEPRESSION

BRIDGE APPROACH DEPRESSIONS

BRIDGE APPROACH GPR DATA


ROADWAY DEPRESSION GPR DATA


SUMMARY• GEOPHYSICAL TEST BENEFITS;

PROVIDES MORE DATA THAN TRADITIONAL METHODS; NON-DESTRUCTIVE TEST METHOD; REDUCED LANE CLOSURES AND TRAFFIC DISRUPTIONS; INCREASES PROJECT SPEED; INCREASES PROJECT ACCURACY; REDUCES PROJECT COSTS AND OVERRUNS;

• QUESTIONS?


Documents

T11 geophysical testing-landschoot