Additional surface movements above coal longwalls in the post-mining phase: case study based on remote sensing satellite data
摘要
Total extraction mining, such as longwall mining, results in subsidence at the surface above the mined area. It was assumed that subsidence occurs within a relatively short time after mining. Based on theoretical considerations and conventional levelling, it was generally assumed that subsidence stops 3–5 years after mining. Since satellite data images became freely available for research at the end of the last century, surface movements above mined areas can be studied over very long periods of time. This results in new insights. The case study focuses on the coal longwall mines in the Belgian Campine coal district. Mining stopped completely in 1992, when the last mine was closed. The analysis is based on successive remote sensing datasets since 1992. The main conclusion is that surface movements are still recorded more than 30 years after the mines were closed, i.e. much longer than the usual 3–5 years that were assumed. The variation in surface movements in the post-mining phase is also more complex. After a period of further subsidence, the direction of surface movements reverses and an uplift of the surface above the mined areas is observed (relative to the end of the subsidence phase). This uplift is still ongoing in 2025. These new findings have practical implications, as these long-term movements further affect the loading of buildings and other infrastructure, leading to possible new damage. It also has a negative impact on the natural environment, e.g., on surface water management.
Article highlightsIn the post-mining phase, additional surface movements still occur above coal longwall panels. The long-term behaviour has consequence for the stability of buildings, the integrity of infrastructure and the natural environment. Remote sensing satellite data are extremely useful to study surface movements over large areas and during long time periods.