135
mm
RESEARCH ON SURFACE SUBSIDENCE MONITORING WITH INSAR/GPS
DATA FUSION IN MINING AREA
ZHANG Ji-chao 1 ’ *, SONG Wei-dong 1 , ZHANG Ji-xian 2 , SHI Jin-feng 1
1 School of Geomatics, Liaoning Technical University, Fuxin 123000, P.R.China - zmouse@21cn.com
2 Chinese Academy of Surveying & Mapping, Beijing 100039, P.R.China
KEY WORDS: InSAR, GPS, data fusion, mining subsidence monitoring
ABSTRACT:
Mining subsidence monitoring is very important for mining and sustainable development. For monitoring mining subsidence,
Interferometric synthetic aperture radar (InSAR) and GPS technology are very strong complementary. The integration of InSAR and
GPS improves the ability of mining subsidence monitoring both in temporal and spatial domain, and it had become a research focus
in monitoring surface subsidence during resent years. The paper first summarized the current situation of research and application
for InSAR/GPS used in surface subsidence monitoring, then mainly analysed mining subsidence monitoring with InSAR/GPS data
fusion. Finally, some corresponding countermeasures are given in the paper, which shall provide technical support for realizing real
time dynamic monitoring of coal mining-induced subsidence.
1. INTRODUCTION
1.1 The necessity of surface subsidence monitoring in
mining area
Mining-induced surface subsidence is an inevitable problem. It
has much impact on coalmine production safety, environmental
destruction and building distortion. To enforce real-time and
effective monitoring on it, disciplinarian and tendency of the
surface subsidence can be discovered in time, so that it can
provide effective early warnings to district security and
environmental destruction, and instruct the control and
comprehensive management of mining subsidence. Thus,
carrying on the surface deformation monitoring of mining area
plays an extremely important roles in the national economy and
the society development.
1.2 Surface deformation of mining area measurements
At present, there are many kinds of measurements for surface
deformation surveying in mining area (Diao, J., 2005), mainly
including conventional geodetic survey, close-range photo-
grammetry, GPS network, Synthetic Aperture Radar Interfero
metry (InSAR) technique and so on.
Conventional geodetic survey method can exert the advantage
of existing instruments and equipments, and it can meet the
required precision of subsidence monitoring. However, this
method needs the surveyors regularly do the work outdoors and
the field operation workload is burdensome. Besides, the
expense is high, and can only do incontinuous surveying.
Close-range photogrammetry method takes advantages of high
efficiency and reliable precision, and it may observe the earth’s
surface continuously. It is adapt to monitor the surface
deformation for small mining area. But compared with the
conventional geodetic survey method, this method is more
complicated and the photographic apparatus is also more
expensive. * 3
GPS network method has the virtue of having no use for
intervisibility among survey stations, the high positioning
accuracy, the short observation period, the simple operation
process, the all-weather work and so on. But the stability of
leveling points and the density of network settings restrict this
method. Beside, it can only extract the value of surface
subsidence through data interpolation, the approximate
subsidence area must be estimated before surveying.
InSAR technique is a new method used for monitoring the
surface deformation of mining area and gets gradually
development. In this technique, the three dimensional informa
tion of the surface can be extracted by using the phase
information of radar echo signals. The precision of the earth
crust vertical deformation measurements can be increased to
millimeter level through differential InSAR (D-InSAR)
technology. However, in many cases the problem of temporal
decorrelation hampers measurements over longer time intervals
successfully.
1.3 GPS/InSAR fusion technique
By comparison, InSAR and GPS technology are very strong
complementary (Chen, J., 2004). Firstly, GPS belongs to point
positioning, and the length of base line is usually tens to
hundreds of kilometres. Such lower point density cannot meet
the demand for high spatial resolution monitoring of the surface
deformation. InSAR data can apply continuous information of
the entire region surface. The spatial resolution can reach to 20
meters. Secondly, InSAR (spatially differential InSAR) is
sensitive to elevation information of the earth surface owing to
the radar incidence angle effect (Xu, C., 2003), while GPS is
unsubstantial in elevation precision. Thirdly, GPS has high
temporal resolution (highest can be up to 1 Hz), while InSAR
data has a lower temporal resolution (more than 20days
generally, highest only can be 1 day) because of the longer
revisiting period. Fourthly, C & Continuous GPS networks
(CGPS) can provide aerosphere delay effect and satellite orbit
* Corresponding author. ZHANG Ji-chao (1975-), male, lecturer, Ph.D student of Liaoning Technical University, research direction:
3S technology theory and its application. Tel: +86-418-3352501; Fax: +86-418-3351790.
