The Surface Of Coal Mine Subsidence Monitoring By Insar Technology

Xinrong district, Datong, which is rich in coal resources, is one of the important coal-mining areas in Shanxi Province. With much larger limits of mining, Xinrong coal mine is exploited for many years. In recent years, the increases of mining intensity and scale have caused considerable impact on the coal mine geological environment in Xinrong district. The surface of coal mine subsidence because of seam mining would have caused a Lagged effect for two or five years or even longer. The disaster of the active period is much longer. Normally it takes 30-50 years to become gradually stable. So damage it causing is more long term and irreversible. Especially for groundwater destruction, it leads directly to the nearby ground water levels to decline, and the shallow water exhaustion. Due to excessive extraction of groundwater, the ground of coal mine has occursd complex mining subsidence deformation and ground fissure, which would have causesd different degrees of threats and destruction to all kinds of building facilities and arable land upon the mining subsidence deformation.Since 1960s, the first use of Synthetic Aperture Radar Interferometry (InSAR), this technology has become an important and potential technique in measuring the changes of the earth surface. This technology has lots of incomparable advantages as against the conventional measuring technology, such as wider range of sample, shorter time, and higher resolution. The interferogram, acquired by Synthetic Aperture Aadar Differential Interferometry (D-InSAR) technology, can be used to monitor the cm-level or even more tiny surface deformation, which has become one of the most important technical in regional surface deformation monitoring field.Using four scenes of ERS-1/2 SAR images, this paper has monitored the surface of coal mine subsidence in Xinrong district, Datong using InSAR techniques. And then has gotten the surface subsidence results about research area by using D-InSAR techniques. This paper mainly has obtained the research achievements as follows:1. Made a careful research on the imaging principle of SAR, the basic principles and method of InSAR and D-InSAR, and the key technology of data application processing. Made a detailed analysis and discussion on the error sources of surface deformation monitoring, which affected the InSAR technology. And summarized principles in the choice of InSAR interferometric data.2. How to use radar interference measuring method generating DEM. Analysised the interferometric coherence of 6 pairs of InSAR interferometric results which was gotten from the four scenes of SAR images, and got some experience about how to reduce the influence of space and time decoherence: Took the ERS-1/2 SAR system as an example, baseline length was generally preferable to 1/3 of the critical baseline. The length of vertical baseline was preferable to 100m. And the maximum was general not exceed 300m. In sparse vegetation, time decoherence effected to the result of interference cross-spring and summer season was weak. However, affected by freezing or by long and severe cold, time decoherence effected to the result of interference cross-spring and winter season was strong.3. Extracted the surface subsidence area by using D-InSAR technique, and analyzed the results of the deformation:There were 3 deformation areas in Xinrong district from 1993 to 1996 according to D-InSAR technique. Two of them were in Shangshen Jian Township, the other was in Xicun Township. Preliminary judge of the 3 areas were surface subsidence type. And the total deformation was about 16.20km2.