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8/8/2011 1 Monitoring Geohazards Impacting Highway Projects using TDR Kevin M. O'Connor, Ph.D., P.E. GeoTDR, Inc. Westerville, Ohio Geohazards Impacting Transportation in the Appalachian Region Chattanooga August 2011
Transcript of Monitoring Geohazards Impacting Highway Projects using TDR › cegas › geohazards ›...
8/8/2011 1
Monitoring Geohazards Impacting Highway Projects
using TDR
Kevin M. O'Connor, Ph.D., P.E.GeoTDR, Inc.
Westerville, Ohio
Geohazards Impacting Transportation in the Appalachian Region
Chattanooga August 2011
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Cables can be grouted into boreholes or trenches to monitor deformation
TDR Cable Tester
Crimp In Cable
Expansive
Cement Grout
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Battery-operated MTDR unit
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Inactive Mine Subsidence
SR 91, Saltville, Virginia
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NEW ALIGNMENT
TDR MONITORINGCABLE
EXISTING SR91
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PLANT AREA
STATE ROUTE 91
NEW ALIGNMENT
Automated, remote
Early Warning
Public safety
Maintain highway access
Limit Liability
Construction Safety
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DAS 1 DAS 2
DAS 3
DAS 4
CO. RD. 745
SR 91Precise Level Monuments
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Total Subsidence SR-91 by Precise Level Survey (1995-2003)
-180.0
-160.0
-140.0
-120.0
-100.0
-80.0
-60.0
-40.0
-20.0
0.0
-20 0 20 40 60 80 100 120 140 160 180 200
Distance (meters)
Vert
ical
mov
emen
t (m
illim
eter
s)
HY-91 HY-91A B11 B10 B9 B8 B-7 B1 B2 B3 FD FC FBFA B4 B5 B67/7/95
6/11/986/14/20006/26/20011/10/2002
7/14/2003
0.06 mm/day
0.03 mm/day
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Cable TDR1
Shearat
10 ft
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0
5
10
15
6/1/2001 7/1/2001 7/31/2001 8/30/2001 9/29/2001 10/29/2001 11/28/2001 12/28/2001 1/27/2002 2/26/2002 3/28/2002
DEF
ORM
ATIO
N. m
m
Precipitation events7/27 and 7/30
Precipitation event 8/27
TDR1 Shear at 10 ft
0.04 mm/day 0.02 mm/day 0.01 mm/day
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Karst Sinkhole Subsidence
I-70 Interchange
Frederick, Maryland
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SITE
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Karst Sinkhole Subsidence
I-70 Interchange
Frederick, Maryland
Automated remote
Extensive area
DoT O&M monitor effectiveness of stabilization
Public safety
Early warning
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subsidence
Long Mine
Abandoned Mine Subsidence
I-70, Muskingum Co., Ohio
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124+00 131+00
131+00 148+00
DAS at 138+00
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Coaxial Multiplexer
ModemTDR Cable Tester
Programmable Data Logger
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EBPA
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
0 500 1000 1500 2000 2500
Distance along cable, ft
Ref
lect
ion
Mag
nitu
de, r
ho
6/16/2010 6/27/2010 6/30/2010
end of cable at 1760 ft
crimps
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-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
0 100 200 300 400 500 600
Ref
lect
ion
Coe
ffici
ent,
rho
Distance, m
EB Passing Lane Trench B
Current Baseline Difference
baseline
current
difference
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Abutment Slope Movement
I-64, Sulphur, Indiana
Forensic
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Fill
Silty Clay LayerSoft Shale
Limestone
TDR Cable
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Fill
Silty Clay
Soft ShaleLimestone
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Typical Costs MTDR unit $3,600 Cable on Spool $1/ft Remote DAS $10,000
INSTALLED CABLE COST Trench $7/ft Vertical hole $15-$25 /ft Angled hole $30-$45 / ft Inside inclinometer casing $3-$5 /ft
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Monitoring Geohazards Impacting Highway Projects
using TDR
Kevin M. O'Connor, Ph.D., P.E.GeoTDR, Inc.
Westerville, Ohio
Geohazards Impacting Transportation in the Appalachian Region
Chattanooga August 2011
