innovative methods of measuring discontinuities...june, 2013 objectives • comparison of rock slope...

I-90 Rockfall Mitigation – West of Drexel RFP Project No: IM 90-1(201)24

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Innovative Methods of Measuring Discontinuities

Nicholas J. Farny

Engineering Geologist Fisher and Strickler Rock Engineering

Utilizing LiDAR and Smartphone Applications for Rock Slope Stability on Price Mountain, VA

Geohazards Impacting Transportation in Appalachia 13th Annual Technical Forum July 30 to August 1, 2013

Harrisonburg, VA


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Outline

• Objectives • Rock Slope Stability Overview • Location • Field Methods • LiDAR Point Cloud Processing • Stereonet Analysis • Conclusions


Harrisonburg, VA


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Objectives

• Comparison of rock slope discontinuity orientation measurements from:

1) Brunton compass 2) Smartphone Application GeoID 3) Ground Based LiDAR • Brunton is the control • Compare overall accuracy


Harrisonburg, VA


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Rock Slope Stability Overview • Safety and economic

design of man made rock slopes

• Stability Controlling Factors: 1. Orientation (dip and

dip direction) of discontinuities

2. Shear strength 3. Water content


Harrisonburg, VA


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Planar Failure

Wedge Failure

Toppling Failure


Harrisonburg, VA


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Harrisonburg, VA


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Field Methods

1) Window Mapping – 2 x 100 foot windows – Discontinuity

orientations measured using:

1. Brunton Compass 2. Smartphone with GeoID


Harrisonburg, VA


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2) LiDAR – Light Detection and

Ranging – Illuminate target surface

with laser pulses – Uses travels time and

speed of light to find distance to target

– Generates 3D point clouds of xyz data

– Ground based scanner

Field Methods


Harrisonburg, VA


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LiDAR Point Cloud Processing

1) Leica Cyclone – LiDAR scanner data to xyz .txt files – Removal of unnecessary data points

2) Split-FX by Split Engineering

– Finds orientation data of discontinuities from LiDAR point clouds

Geohazards Impacting Transportation in Appalachia 13th Annual Technical Forum

July 30 to August 1, 2013 Harrisonburg, VA


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Window 1

Window 2


Harrisonburg, VA


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Window 2

Window 1


Harrisonburg, VA


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Window 1

Window 2


Harrisonburg, VA


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Window 1 Window

1

Window 2


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• Missing/incorrect patches

• Needs ground truthing


Harrisonburg, VA


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Stereonet Analysis

• Contouring • Set

identification • Average set

orientation calculations

• Kinematic Stability


Harrisonburg, VA


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Window 1 Brunton

Window 1 Smartphone


Harrisonburg, VA

Discontinuities Displayed as Poles


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Window 1 Brunton

Window 1 LiDAR


Harrisonburg, VA



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Method Bedding Joint Set A Joint Set B

Brunton 69/325 41/109 37/160

Smartphone

68/323 42/110 37/165

LiDAR 77/319 45/115 45/161

Window 1 Dip/Dip Direction Summary


Harrisonburg, VA


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Window 2 Brunton

Window 2 Smartphone


Harrisonburg, VA



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Window 2 Brunton

Window 2 LiDAR


Harrisonburg, VA



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Method Bedding Joint Set A + B

Brunton 61/335 47/155

Smartphone 58/333 46/150

LiDAR 63/337 51/156

Window 2 Dip/Dip Direction Summary


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Planar Failure

Window 1 Window 2

30 degree Friction Angle for Poles

Vertical Slope Face

Critical Zone for Poles


Harrisonburg, VA



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Window 2 Brunton

Wedge Failure

Primary Critical Zone for Dip Vectors

Vertical Slope Face 30 degree Friction Angle for

Dip Vectors

Window 1 Window 2


Harrisonburg, VA


Secondary Critical Zone for

Dip Vectors


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Window 2 Brunton

Window 2 LiDAR

Toppling Failure

Window 1 Window 2

30 degree Friction Angle for Base Plane Poles

Vertical Slope Face

Critical Zone for Dip Vectors and Base Plane

Poles


Harrisonburg, VA



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Conclusions • Close agreement of Brunton and Smartphone • LiDAR can capture all of a rock slope in less

time • Split-FX automated discontinuity identification

= needs to be calibrated with field measurements

• LiDAR works best on large prominent discontinuities

• Remote sensing techniques like LiDAR do not replace traditional field surveys and geologic experience


Harrisonburg, VA


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Questions?


Harrisonburg, VA

innovative methods of measuring discontinuities...june, 2013 objectives • comparison of rock slope...

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