monitoring mining induced subsidences using gps …...monitoring mining induced subsidences using...

TS 48 – Engineering Surveys for Construction Works II 1/12 Hakan Akçin, Tomonori Degucci and Hakan S. Kutoglu Monitoring Mining Induced Subsidences Using GPS and InSAR Shaping the Change XXIII FIG Congress Munich, Germany, October 8-13, 2006

Monitoring Mining Induced Subsidences Using GPS and InSAR

Hakan. AKÇIN, Turkey, Tomonori. DEGUCCI , Japan and Hakan.S. KUTOĞLU, Turkey

Keywords: Mining, subsidence, GPS, InSAR, JERS-1 SAR, RADARSAT SUMMARY Underground mining causes subsidence effect on the earth surface. It is possible to monitor this effect by geodetic surveying methods. However, these methods have some difficulties to apply in places where topography is hilly or forestry or dense urbanization is available. These difficulties can be overcome using InSAR technique to monitor subsidence effects. In order to study the performance of InSAR on determining subsidence effects, an investigation has been carried out in Kozlu region of Zonguldak Hardcoal Basin, Turkey. Using JERS-1/SAR and RADARSAT images subsidence areas and amounts have been determined. These results obtained from InSAR have been compared those obtained from GPS observations of a geodetic control points established in the region. This comparison shows that GPS and InSAR results are consistent with each other.

TS 48 – Engineering Surveys for Construction Works II Hakan Akçin, Tomonori Degucci and Hakan S. Kutoglu Monitoring Mining Induced Subsidences Using GPS and InSAR Shaping the Change XXIII FIG Congress Munich, Germany, October 8-13, 2006

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Monitoring Mining Induced Subsidences Using GPS and InSAR

Hakan. AKÇIN, Turkey, Tomonori. DEGUCCI , Japan and Hakan.S. KUTOĞLU, Turkey

1. INTRODUCTION In many countries that coal mining is applied, surface subsidence caused by mining activities has been carefully monitored, and some precautions intended for surface damages by the subsidence have been taken into consideration. However, subsidence is a complex event which is a result of natural and unnatural effects although it is taken place due to the underground productions. The regional behavior of this event can be investigated by observation techniques applied over the earth surface and/or under the earth. In this study, InSAR and GPS techniques are integrated to monitor the surface changes caused by the subsidence in Zonguldak city, which is the biggest hard coal basin in Turkey. In Zonguldak Hardcoal Basin (ZHB), production activities have been continued since the year of 1848. Up to now the raw coal about 400 million ton has been extracted from the basin which has the area of 15000 km2 whose 3000 km2 is under the sea. In this basin, the coal seams are limited to the upper carbonifer layers. These layers, whose total thickness changes between 600-800 m, have a very complex geological structure. The coal production in the region has been carried out in the production panels with different geometrical pattern and different height, using different production techniques. Kozlu region treated in this study is one of the oldest production areas of the basin. The location of the basin and the investigation area in this basin are given in Fig. 1.

Fig.1. Location of study area

TURKEY

Zonguldak City Study Area

BLACK SEA

MEDITERRANEAN SEA


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At the beginning of this study, a deformation map is formed by differential application of two different images in 1995 taken from JERS-1/SAR satellite (Fig. 2). In this map five deformation zones have been detected. The four of these zones are in the forestry area which is not appropriate to apply GPS observation technique. The only urban area which the Fig. 2. The image above shows deformation surface obtained from JERS-1 satellite. The image below

is ASTER infra-red image of the region.

KOZLU HARDCOAL

BASIN

FORESTRY AREA

URBAN AREA

SURFACE SUBSIDENCE

BLACK SEA

BLACK SEA


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subsidence is observed is related to the Kozlu region. In this area, a GPS network has been established to confirm the deformations detected by InSAR technique.

In addition, the digitized coal production plans are used for determining whether the deformations obtained coincide with the subsidence effect area or not. When the subsidence mechanism in the region is investigated it is observed two constitutions in the direction of and the perpendicular direction to the production (Fig.3 and Fig. 4). It is known that this mechanism is induced by the constant factors relating to geological structure and the variable factors relating to the geometry of production area (Whittaker, B. N. ve Reddish D. J., 1989). For GPS and InSAR observations, determining the area which subsidence affects on the earth surface is an important issue. The effect area on the earth surface can be determined when the dimensional parameters of the panel constituted in the gallery mined, i.e. width and length of the panel, thickness of the gallery, and lower and upper heights of the panel, are known (Fig. 5).

Fig.3. Subsidence constitution mechanism in the direction of production (adapted from Shadbold, C. H., 1977)

γ Subsidence Limit

Angle

Production Area

Coal Seam

GPS points on surface under subsidence effect

GPS points on orginal surface

Convergent of layers in production area

x

z


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SURFACESurface on Subsidence effect

36O

Fig.4. Subsidence mechanism in the perpendicular direction of production 2. DETERMINATION OF THE PRODUCTION EFFECTS AREAS IN KOZLU TEST AREA In order to determine which production activities affects on the surface deformations to be obtained by InSAR ve GPS observations, underground production plans has been digitized, and effects areas of the coal productions after 1995 have determined. Fig. 6 shows the production panels and their effect areas between the heights of -200 m and -400 m between 1995 and 2001. 3. OBTAINING SUBSIDENCE EFFECTS IN KOZLU USING GPS AND INSAR TECHNIQUES Geodetic control points on the earth surface can be deformed with time due to tectonic movements and/or underground mine productions. Observing the control points repeatedly by geodetic surveying techniques such as GPS, horizontal (vX, vY) and vertical (vH) components of deformations in relation to the point coordinates X, Y and H can be obtained. Analogously, applying differential InSAR application to radar images in two different instant, deformation vectors can be obtained. For such an investigation, two period GPS observations in 1996 and 2003 carried out on the available network in Kozlu region have been utilized, and the first result for the subsidence effect have been obtained. After 2005 the number of the control points has been increased to obtain more detailed deformation knowledge. Fig. 7 and Fig. 8 show old and new constitutions of the geodetic network. The deformation vectors obtained from the 1996 and 2003 observations are illustrated in Fig. 9. In order to obtain the surface deformations by InSAR technique, two images taken with an interval of 132 days in 1996 have been used, and deformation areas given in Fig. 10 have been determined. Fig. 11 shows the regression graphics of deformation slant ranges obtained


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from GPS and InSAR. Fig.12 also shows deformation vectors obtained from both methods, GPS and InSAR, in 2005.

Fig.5. Subsidence constitution and its effect area from different profiles in a horizontal seam (adapted

from Peng, 1992).

COAL

SEAM

COAL SEAM

L1 LD L2

L 3

L Y

L 4

b

a

PRO

DU

CTI

ON

A

REA

SUR

FAC

E

SUB

SID

ENC

E PR

OFI

LE

SURFACE

SUBSIDENCE PROFILE

CO

AL

S

EA

M

PRODUCTION AREA

R

P

NM

R

M N

P R

P

M N

γ SUBSIDENCE

LIMIT ANGLE


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Fig.6. Effect areas of the panels on Cay and Kurul seams

Fig.7. Control points used between1995 and 2003

10

644

6666 643

11

642

641

N

ÖLÇEK

4400.00 4600.00 4800.00 5000.005200.005400.005600.005800.006000.006200.00 6400.00

90000.00

90200.00

90400.00

90600.00

90800.00

91000.00

91200.00

91400.00

91600.00

0.00 500.00 1000.00 1500.00 2000.00

3 5

10

643 11

642

6666

Influence Boundary of Mine Productions between 1995-2001


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Fig.8. Extended network after 2005

4400.00 4600.00 4800.00 5000.00 5200.00 5400.00 5600.00 5800.00 6000.00 6200.00 6400.00

90000.00

90200.00

90400.00

90600.00

90800.00

91000.00

91200.00

91400.00

91600.00

Fig.9. Deformation vectors obtained between 1996-2003

Horizontal Velocities

Vertical Velocites

0,5 m /7 year

0,5 m / 7 year

642

643

644

10

11 6666

641

5 3


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Fig. 10. Deformations obtained from InSAR in 1996

Fig. 11. Regression graphics of deformation slant ranges obtained from GPS and InSAR with an interval of 132 days in 1996

12cm/5month0cm/5month

R2 = 0,7894

-30

-20

-10

0

10

20

30

40

50

60

-20 0 20 40 60

Seri 1Polinom (Seri 1)

GPS (slant range)

InSAR (slant range)


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5. CONCLUSIONS Subsidence which is an important issue of underground mining is a three dimensional deformation event which occurs due to collapsing layers from underground production plane to the earth surface. Since subsidence is a destructive event like earthquakes its advance with time must be monitored using proper methods. In this study, the subsidence effects on Kozlu region in ZHB which happen between 1996-2003 and between 2005-2006 have been investigated using GPS and InSAR techniques. In conclusion, the followings have been obtained: − JERS-1/SAT and RADARSAT have been provided consistent results with GPS. In this

way, spatial and temporal details have been possible to produce in Kozlu region. − In the same parallel with GPS, diferential InSAR analyses have been provided to monitor

the deformation in short periods such as 0-5 month − Subsidence effects in places where GPS method can not be applied have been

successfully determined by InSAR Finally, in the light of the findings above, it can be said that high accuracy subsidence monitoring can be performed with an effective cost using InSAR technique. REFERENCES Ge, L., Rizos C., Han S. and Zebker H., (2001). Mining subsıdence monıtorıng using the

combined InSAR and GPS approach, The 10th FIG International Symposium on Deformation Measurements, California USA.

Hirose K., Maruyama Y., Murdohardono D., Efendi A., Abidin Z. H., (2001). Land subsidence detection using JERS-1 SAR interferometry, 22nd Asian Confernce On Remote Sensing, Singapore

Peng, S. S., (1992). Surface Subsidence Engineering, 159 sh., Published by Society for mining, metalurgy, and exploration, Inc., Littelon, Colorado.

Shadbold C. H., (1977). Minining subsidence – historical review and state-of-the-art.Proc. Conf. Large Ground Movements, 705-748 sh., UWIST, Cardiff. Ed. J. D. Geddes, Pentech Pres, London Plymouth.

Whittaker B. N., Reddish D. J., (1989). Subsidence occurrence, prediction and control,528 sh., Elsecer, Amsterdam-Oxford-New york-Tokyo.


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Fig.12. Deformation vectors obtained from both methods, GPS and InSAR, in 2005

Vertical velocity from GPS observations 2cm / 4 month

Vertical velocity from InSAR

/ 4 month


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CONTACTS H. Akçin and H.S. Kutoğlu Zonguldak Karaelmas Üniv Müh. Fakültesi, Jeodezi ve Fotogrametri Müh Bölümü 67100, 2 TURKEY Email: [email protected], [email protected] T. Degucci Earth Remote Sensing Analysis Center (ERSDAC) Forefront Tower 14F, 3-12-1,Kachidokin Chuo-ku 104-0054 Tokyo JAPAN Email: [email protected]

monitoring mining induced subsidences using gps …...monitoring mining induced subsidences using...

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