3D and 2D radars for open pit slope monitoring - BOHOGS · 2015. 12. 3. · 3D-RAR 2D-SAR 2D-RAR...

3D and 2D radars for open pit slope monitoring Albert Cabrejo, Product Manager (GroundProbe)

Acknowledgments

From GroundProbe: • Patrick Bellett – Principal Scientist • David Noon – VP Sales & Operations From LisaLabs • Davide Leva – Principal Scientist • Carlo Rivolta - CEO

Introduction and Background

• Real Aperture Radar (RAR) vs Synthetic Aperture Radar (SAR) • Radar dimensionality – 3D and 2D radars

3D-RAR 2D-SAR 2D-RAR

Tactical (targeted) and strategic (broad area) Safety-critical and background monitoring

Rapid-brittle and slow-ductile failures Bench-scale, multi-bench scale, total slope failures

All radars (3D-RAR, 2D-SAR and 2D-RAR) are capable to monitor all these combinations

Each has particular strengths and trade-offs as well

• Balanced comparison of 3D-RAR, 2D-SAR and 2D-RAR • Co-authors (Drs Bellett, Leva and Rivolta)

MONITORING STRATEGIES EFFECTIVE USES OF SLOPE STABILITY RADAR

Monitoring Strategies

Targeted Monitoring

Broad Area Monitoring

• Monitor known risks and hazards

• Highly mobile • Flexible positioning • Safety-critical for

small/large rapid-brittle failures

• Find new risks and hazards

• Often left at crest or mid-slope

• Longer term monitoring

• Safety-critical and background for large slow failures

Targeted and Broad Area Monitoring Systems

3D Real Aperture Radar (RAR) Dish antenna Pencil beam – small spot on the wall Scans a spot in azimuth and elevation Each spot is also sliced in range Highest confidence for targeted area

2D Synthetic Aperture Radar (SAR) Small antennas on rail

Vertical beam – thin stripe on wall Each stripe segmented by range

Fixed view forward Longest range

Highest resolution

2D Real Aperture Radar (RAR) Long antennas

Vertical beam – thin stripe on wall Each stripe segmented by range

Rotates the stripe in azimuth (fast) Broadest area covered per unit of time

3D-RAR 3D Radar sees the world in 3D and generates a radar 3D DTM

Azimuth°

Ele

vatio

n°

3D-RAR

Azimuth°

Ele

vatio

n°

3D Radar sees the world in 3D and generates a radar 3D DTM and projects naturally to front view

3D-RAR with native front view visualisation

3D-RAR with native 3D visualisation

Photograph draped over 3D radar DTM

3D-RAR with native 3D visualisation

Deformation image draped over 3D radar DTM

3D-RAR with native 3D visualisation

Photograph & deformation image draped over 3D radar DTM

2D-RAR

Long antennas

Thin, tall, vertical stripe ~0.5° wide and ~60° tall

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2D Radar with natural plan view image

eg. SSR-FX: 60/180 degrees in 2 minutes Azimuth pixels ~ 0.125°/0.5° Range pixels ~ 0.67 m

180°

180°

Broad area monitoring in Plan view

Broad area monitoring in Plan view

Broad area monitoring in Plan view

2D-SAR

Small antennas Horizontal translation

The 2D-SAR generates a broad beam that synthesizes narrow beams in a fixed field of view.

eg. SSR-SARx bench-scale at 4.5km range

Long range monitoring 2D-SAR

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Long range monitoring 2D-SAR 2mm over 14 days

5mm over 14 days

• 2nd periodical check 6-15 september 2015

Periodic monitoring with 2D-SAR

1st PC 5mm

2nd PC 60mm

Permanent monitoring

Periodic monitoring with 2D-SAR

Conclusions

3D and 2D radars can be used for targeted and broad area monitoring – but each has a strength:

For targeted monitoring of known high risk areas… 3D-RAR provides high confidence for targeted monitoring Front-view display - users can tactically view the slope as if looking

from front-on.

For very broad area monitoring to detect new risk areas …

2D-RAR provides very broad angle coverage quickly Plan-view display - users can strategically view the slope with

reference to other mine geospatial maps (eg. aerial photograph, mine plan, hazards map).

Conclusions

For very long range monitoring … 2D-SAR provides up to 4.5km range over a fixed angle of view

For monitoring slopes with very slow rates of movements… 2D-SAR hardware is easy to relocate and geo-reference so small

movements in-between monitoring periods can be measured.

For some mines, an integrated solution using some or all of

the available radar monitoring technologies (3D-RAR, 2D-SAR and 2D-RAR) together with non-radar monitoring technologies will provide the most comprehensive monitoring strategy

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