Comment
Author: Admin | 2025-04-27
2e shows the rate of movement of the points above and at the borders of panel C.During mining panels A and B (until about 2 years), the rates of movement of the two different points (c and d) were significantly less than what was observed for the points above and at the borders of panel A (Fig. 2c). However, while panel C was being mined, point c around the middle of the panel underwent a higher rate than was observed previously. The largest average monthly rate that was recorded was − 2.5 mm/day for point c (2.62 years). As mentioned above, the largest average rate recorded at reference point a was − 1.8 mm/day (0 year).3 Variation as a function of time over the entire life span of the mine, including the long-term impactThe previous paragraph focused on the initiation of the vertical movement of the surface or the subsidence when beginning to mine coal or when opening a new section of an existing mine. The measurements were frequent (about monthly) and the distances between measuring points were relatively small (from 100 to 250 m). The points were situated along a single straight line, which was relatively short, i.e., a total of 2.3 km, but movement was observed over a length of about 1 km. The total observation period was limited to about 4 years. In this paragraph, data are presented for a total observation period of 54 years. The frequency of the measurements was much less, i.e., every 5–10 years. Figure 3 shows that the length of the measuring line with movement was about 2.5 km. All measuring points for the levelling campaign were anchored at the bottom part of buildings. Hence, the roads were followed, resulting in a non-straight line. The vertical movements were measured in comparison to a reference point that was situated about 900 m more to the northeast than point A along the same road, i.e., A–B–C (De Mey 1986). These levelling data were complemented with recent remote sensing observations by satellites. Even though the frequency of the latter recordings was close to monthly, the same time interval is presented that was used for the levelling data.Fig. 3Map of the measurement line with the various measurement pointsFull size imageAs mentioned earlier, the mining took place in the Belgian Campine basin along a relatively narrow east–west band over a length of several 10’s of km with
Add Comment