Inversion and Analysis of Mining Subsidence by Integrating DInSAR, Offset Tracking, and PIM Technology

Xiaobo Xu,Dezheng Zhao,Dajun Lian,Chao Ma

doi:10.1155/2020/4136837

Abstract

High-intensity underground mining generates considerable surface subsidence in mining areas, including ground cracks and collapse pits on roads and farmland, threatening the safety of buildings. Large-amplitude subsidence (e.g., >2 m) is usually characterized by a large phase gradient in interferograms, leading to severe phase decorrelation and unwrapping errors. Therefore, the subsidence on the surface cannot be well derived simply using conventional differential interferometric synthetic aperture radar (DInSAR) or other geodetic measurements. We propose a new method that combines both DInSAR and subpixel offset-tracking technology to improve mine subsidence monitoring over large areas. We utilize their respective advantages to extract both the spatial boundaries and the amplitude of displacements. Using high-resolution RADARSAT-2 SAR images (5 m) acquired on February 13, 2012, and November 27, 2012, in the Shendong Coalfield located at the border between Shaanxi Province and Inner Mongolia Province, China, we obtain the subcentimetre-level subsidence of the mine boundary by DInSAR and resolve the metre-level mine subsidence centre based on subpixel offset tracking. The whole subsidence field is obtained by combining and analyzing the subcentimetre-level and the metre-level subsidence. We use the probability integral method (PIM) function model to fit the boundary and central mine subsidence to reconstruct the spatial distribution of the mine subsidence. Our results show that the maximum central subsidence reaches ~4.0 m (beyond the monitoring capabilities of DInSAR), which is generally in agreement with the maximum subsidence of ~4.0-5.0 m from field investigation. We also model the boundary and the central subsidence (the final fitting coefficient is 0.978). Our findings indicate that the offset-tracking method can compensate for the deficiency of DInSAR in large-amplitude subsidence extraction, and the inclusion of the PIM technique helps reconstruct the whole subsidence field in mining areas.

Highlights

Large-scale exploitation of coal resources meets the increasing demands of regional economic development
Using RADARSAT-2 SAR image pairs acquired on February 13, 2012, and November 27, 2012 (Table 1), and SRTM digital elevation model (DEM) v3.0 (90 m) data, the deformation field due to surface subsidence in the mining area that occurred during the observation period was derived using the radar interferometry software GAMMA (GAMMA Remote Sensing Research and Consulting AG, Gümligen, Switzerland; http://www.gamma-rs.ch/)
The results are generally consistent with the maximum mining subsidence of ~4.478 m in the same mining area presented by Fan et al [50] using 11 TerraSAR-X SAR images acquired from 13 December 2012 to 2 April 2013 based on a subpixel offset-tracking method. It is in agreement with the result by Wang et al [51] which obtained the maximum subsidence value of ~4.5 m based on the offset-tracking technology using TerraSAR-X images acquired in the same time period

Summary

Introduction

Large-scale exploitation of coal resources meets the increasing demands of regional economic development. It results in serious ecological, environmental, and geological problems. Ground subsidence in mining areas has caused a series of geological disasters, which brings potential dangers related to the construction of mining areas, including threats to water resources, transportation infrastructure, and farmland. The Shendong mining area, located at the border between Shaanxi Province and Inner Mongolia Province, has sufficient coal resources with shallow buried depth (average mining depth of ~260 m) and small coal seam thickness (2.2–2.9 m, 2.5 m on average). Ground subsidence caused by coal mining in this area has the same characteristics as that caused by high-intensity mining, such as high subsidence rates

Methods

Results

Conclusion