4
PHASE OF UPSIDENCE ABOVE A NORTH-
SOUTH ORIENTATED MINED ZONE (COAL
MINES OF WINTERSLAG AND ZWARTBERG)
At the SME 2017 International Conference on Ground
Control in Mining (Vervoort and Declercq 2017), a case
study was presented with measurements of the upward sur-
face movements or uplift above two neighboring coal mines
(Winterslag and Zwartberg, Belgium). The Zwartberg mine
was closed in 1966, and the Winterslag mine in 1988. Five
years later, at the SME 2022 International Conference on
Ground Control in Mining, the results of the analytical
calculations and a comparison with the measurements for
the same case were presented (Vervoort 2022a). Readers are
referred to both papers for all details on the mining opera-
tion and the results of the analysis. This paper complements
the previous analysis with the newly available EGMS-data,
including the measurement of east-west horizontal sur-
face movements. In the Campine coal basin, mining took
place in a relatively narrow east-west band (with a north-
south width of about 5 to 7 km and a length of about 50
to 60 km). The strata are dipping to the north. Therefore,
the analysis was based on 2D north-south transects. The
variation of the vertical surface movement is much greater
in the north-south direction than in the east-west direc-
tion. Based on this finding, a logical assumption would
be that the variation of the horizontal surface movement
would also be smaller in an east-west direction than in a
north-south direction. However, it must be admitted that
very little is known about horizontal surface movements,
associated with subsidence or upsidence over deep under-
ground coal mines. Horizontal strain is sometimes taken
into account in studies, but rather as a derivative of the
vertical subsidence curve. Samsonov et al. 2013 published
some results of horizontal movements above coal longwalls,
recorded by satellite images.
Figure 3 shows the zone discussed in this and previous
two papers (Vervoort and Declercq 2017 Vervoort 2022a).
The map shows all superimposed panels. The latter are
located between a latitude of 50.965° and 51.03°. A period
of 5 years is chosen, i.e., from November 2016 through
November 2021. In Figure 4a, all data points above the
mined zone of Figure 3 are analyzed and the vertical vs. the
horizontal east-west movements are compared. Most values
are between an additional 6 to 15 mm of vertical movement
over 5 years (or an average rate of 1.2 to 3 mm/year). Both
larger and smaller values are observed, but these are almost
all positive. The recorded horizontal surface movements for
this zone are mainly between -1 and -9 mm over the 5-year
period. A negative movement value means a movement to
the east.
Data points in a zone north and south of the mined
zone are also studied (Figure 4b). Both zones are outside the
zone of influence. The distribution of the horizontal move-
ment is similar, as in Figure 4a (i.e., above the mined zone).
However, the vertical movements are completely different
between the two graphs. Away from the mined zone, most
data points are situated between plus and minus 3 mm of
vertical movement over a 5-year period, i.e., ±0.6 mm/year.
In conclusion, the phenomenon of upsidence or uplift is
clearly related to past mining, as previously shown (see the
list of references in Vervoort 2021a). The new recent dataset
clearly shows that this conclusion is still valid more than 30
years after the closure of the underground mine.
As mentioned above, the largest variation in vertical
surface movements is observed in the north-south direc-
tion. Figure 5 presents data for 5-year periods from each
of the available remote sensing satellite images. All reflec-
tors situated within a 500 m band around the longitude of
5.495° are shown as a function of the north-south latitude.
Figure 3. Map of all longwall panels mined (presented
superimposed) in part of the concession of the coal mines
Winterslag and Zwartberg (Vervoort and Declercq 2017)
blue dotted line: border between the two mines stars:
average position of double central shafts (Winterslag
in purple and Zwartberg in brown) longwall panels
superimposed in grey faults indicated in green, red and
thick black lines.
PHASE OF UPSIDENCE ABOVE A NORTH-
SOUTH ORIENTATED MINED ZONE (COAL
MINES OF WINTERSLAG AND ZWARTBERG)
At the SME 2017 International Conference on Ground
Control in Mining (Vervoort and Declercq 2017), a case
study was presented with measurements of the upward sur-
face movements or uplift above two neighboring coal mines
(Winterslag and Zwartberg, Belgium). The Zwartberg mine
was closed in 1966, and the Winterslag mine in 1988. Five
years later, at the SME 2022 International Conference on
Ground Control in Mining, the results of the analytical
calculations and a comparison with the measurements for
the same case were presented (Vervoort 2022a). Readers are
referred to both papers for all details on the mining opera-
tion and the results of the analysis. This paper complements
the previous analysis with the newly available EGMS-data,
including the measurement of east-west horizontal sur-
face movements. In the Campine coal basin, mining took
place in a relatively narrow east-west band (with a north-
south width of about 5 to 7 km and a length of about 50
to 60 km). The strata are dipping to the north. Therefore,
the analysis was based on 2D north-south transects. The
variation of the vertical surface movement is much greater
in the north-south direction than in the east-west direc-
tion. Based on this finding, a logical assumption would
be that the variation of the horizontal surface movement
would also be smaller in an east-west direction than in a
north-south direction. However, it must be admitted that
very little is known about horizontal surface movements,
associated with subsidence or upsidence over deep under-
ground coal mines. Horizontal strain is sometimes taken
into account in studies, but rather as a derivative of the
vertical subsidence curve. Samsonov et al. 2013 published
some results of horizontal movements above coal longwalls,
recorded by satellite images.
Figure 3 shows the zone discussed in this and previous
two papers (Vervoort and Declercq 2017 Vervoort 2022a).
The map shows all superimposed panels. The latter are
located between a latitude of 50.965° and 51.03°. A period
of 5 years is chosen, i.e., from November 2016 through
November 2021. In Figure 4a, all data points above the
mined zone of Figure 3 are analyzed and the vertical vs. the
horizontal east-west movements are compared. Most values
are between an additional 6 to 15 mm of vertical movement
over 5 years (or an average rate of 1.2 to 3 mm/year). Both
larger and smaller values are observed, but these are almost
all positive. The recorded horizontal surface movements for
this zone are mainly between -1 and -9 mm over the 5-year
period. A negative movement value means a movement to
the east.
Data points in a zone north and south of the mined
zone are also studied (Figure 4b). Both zones are outside the
zone of influence. The distribution of the horizontal move-
ment is similar, as in Figure 4a (i.e., above the mined zone).
However, the vertical movements are completely different
between the two graphs. Away from the mined zone, most
data points are situated between plus and minus 3 mm of
vertical movement over a 5-year period, i.e., ±0.6 mm/year.
In conclusion, the phenomenon of upsidence or uplift is
clearly related to past mining, as previously shown (see the
list of references in Vervoort 2021a). The new recent dataset
clearly shows that this conclusion is still valid more than 30
years after the closure of the underground mine.
As mentioned above, the largest variation in vertical
surface movements is observed in the north-south direc-
tion. Figure 5 presents data for 5-year periods from each
of the available remote sensing satellite images. All reflec-
tors situated within a 500 m band around the longitude of
5.495° are shown as a function of the north-south latitude.
Figure 3. Map of all longwall panels mined (presented
superimposed) in part of the concession of the coal mines
Winterslag and Zwartberg (Vervoort and Declercq 2017)
blue dotted line: border between the two mines stars:
average position of double central shafts (Winterslag
in purple and Zwartberg in brown) longwall panels
superimposed in grey faults indicated in green, red and
thick black lines.