5
The selection of 5-year periods within each full time series
makes comparison easier. The limits of the mined zones are
indicated by dotted lines in Figure 5.
The three transects confirm that the upsidence occurs
over the entire mined zone and extends for a relatively short
distance beyond the mined limits. However, there is no dis-
cussion that the phenomenon of upsidence is linked to the
past mining. The rate of upward movement decreases as a
function of time since the closure. However, thirty years
after the closure of the Winterslag coal mine the upward
movement is still clearly visible. The shape of the curves
changes when comparing the three 5-year periods. In
the period 1995–2000, there is a clear maximum in the
curve, i.e., just south of the line between both concessions
(blue dotted line in Figure 5a). In the period 2016–2021,
there is no clear maximum and the additional movement
over the mined area is approximately constant. However,
the northern part of the transect lies above the Zwartberg
mine, which was closed in 1966. The underground of the
Zwartberg mine began to be flooded in 1966. However,
this only happened partially (from a depth of 775 m
downward). Although there were no man-made connec-
tions between the two underground mines, water from
the Zwartberg mine flowed into the underground work-
ings of the Winterslag mine and was pumped to the sur-
face by the installations of the Winterslag mine. Although
there are some minor differences between the data over
the Zwartberg and the Winterslag mine (Vervoort and
Declercq 2017), the upward movement is generally similar
above both mines. For example, for the period 2016–2021,
the 5-year movement above the Zwartberg mine may be a
few mm smaller.
EXAMPLES OF DAMAGE TO BUILDINGS AND
INFRASTRUCTURE, OBSERVED AFTER THE
MINE CLOSURE
The evolution of the surface movements over time is most
likely one of the most complex geotechnical problems. For
the phase of short-term subsidence, text books often look at
the situation in which a single panel is mined. The emphasis
is on the curvature along the edges of the panel. However,
even when mining in a single seam, the variation of the tilt
orientation is an aspect that must be taken into account
(Vervoort 2021c). If the mining geometry is as complex as
observed in the Campine coal basin (Figure 3), the move-
ments are a sequence of rotations, extension, compression,
tilt, etc. For deep coal mines, the phase of short-term sub-
sidence is always followed by a phase of long-term residual
subsidence (e.g., Vervoort 2020b). Although the rate of
movement is much smaller than during the phase of short-
term subsidence, the additional subsidence value should
not be neglected. For example, if the residual subsidence
is 5 mm per year, the additional subsidence after 10 years
is equal to 50 mm, which is considered in Eurocode 7 as
Figure 4. Vertical vs. horizontal surface movements over a 5-year period, based on the EGMS-dataset. a. Data points situated
above mined zone (see Figure 3 Latitude between 50.965° and 51.03°) b. Data points away from mined zone (Latitude
smaller than 50.955° and larger than 51.05°). A negative horizontal movement is towards the east.
(a) (b)
The selection of 5-year periods within each full time series
makes comparison easier. The limits of the mined zones are
indicated by dotted lines in Figure 5.
The three transects confirm that the upsidence occurs
over the entire mined zone and extends for a relatively short
distance beyond the mined limits. However, there is no dis-
cussion that the phenomenon of upsidence is linked to the
past mining. The rate of upward movement decreases as a
function of time since the closure. However, thirty years
after the closure of the Winterslag coal mine the upward
movement is still clearly visible. The shape of the curves
changes when comparing the three 5-year periods. In
the period 1995–2000, there is a clear maximum in the
curve, i.e., just south of the line between both concessions
(blue dotted line in Figure 5a). In the period 2016–2021,
there is no clear maximum and the additional movement
over the mined area is approximately constant. However,
the northern part of the transect lies above the Zwartberg
mine, which was closed in 1966. The underground of the
Zwartberg mine began to be flooded in 1966. However,
this only happened partially (from a depth of 775 m
downward). Although there were no man-made connec-
tions between the two underground mines, water from
the Zwartberg mine flowed into the underground work-
ings of the Winterslag mine and was pumped to the sur-
face by the installations of the Winterslag mine. Although
there are some minor differences between the data over
the Zwartberg and the Winterslag mine (Vervoort and
Declercq 2017), the upward movement is generally similar
above both mines. For example, for the period 2016–2021,
the 5-year movement above the Zwartberg mine may be a
few mm smaller.
EXAMPLES OF DAMAGE TO BUILDINGS AND
INFRASTRUCTURE, OBSERVED AFTER THE
MINE CLOSURE
The evolution of the surface movements over time is most
likely one of the most complex geotechnical problems. For
the phase of short-term subsidence, text books often look at
the situation in which a single panel is mined. The emphasis
is on the curvature along the edges of the panel. However,
even when mining in a single seam, the variation of the tilt
orientation is an aspect that must be taken into account
(Vervoort 2021c). If the mining geometry is as complex as
observed in the Campine coal basin (Figure 3), the move-
ments are a sequence of rotations, extension, compression,
tilt, etc. For deep coal mines, the phase of short-term sub-
sidence is always followed by a phase of long-term residual
subsidence (e.g., Vervoort 2020b). Although the rate of
movement is much smaller than during the phase of short-
term subsidence, the additional subsidence value should
not be neglected. For example, if the residual subsidence
is 5 mm per year, the additional subsidence after 10 years
is equal to 50 mm, which is considered in Eurocode 7 as
Figure 4. Vertical vs. horizontal surface movements over a 5-year period, based on the EGMS-dataset. a. Data points situated
above mined zone (see Figure 3 Latitude between 50.965° and 51.03°) b. Data points away from mined zone (Latitude
smaller than 50.955° and larger than 51.05°). A negative horizontal movement is towards the east.
(a) (b)