2
the exploration of ever deeper ore deposits faces challenges
that require solutions such as the development of advanced
ventilation systems and geotechnical techniques to stabilize
underground structures to name only a few. In order to
conceptualize, design, construct, and work safely in under-
ground structures, it is imperative to be able to simulate
different scenarios in models. A digital twin is well-suited to
coupling different inputs, e.g., physical parameters, partly
based on real-time data, to simulate scenarios that could
occur in natural underground spaces.
Therefore, the MOVIE project aims to combine four
models, namely geological, geomechanical, geometrical
and ventilation, to create an artificial intelligence (AI)-
supported coupled model in which physical parameters
and boundary conditions can be changed to visualize the
effects. In virtual reality, the underground space can be
experienced and different parameters can be changed in real
time. This digital twin is based on an underground labora-
tory located in a former silver mine in Germany. Model
parameters are obtained from measurements in the under-
ground laboratory using fiber-optic sensing cables to moni-
tor temperature changes and the deformation induced in
different experimental setups.
METHODS
The Natural Lab: Research and Educational Mine
“Forschungs- und Lehrbergwerk Reiche Zeche”
The mine used for the construction of the underground
laboratory is the “Forschungs- und Lehrbergwerk (FLB)
Reiche Zeche” at TU Bergakademie Freiberg (TUBAF)
in Germany, part of the former silver/lead/zinc mine
“Himmelfahrt Fundgrube,” whose beginnings date back
to the 13th century [3]. Today, the mine is used in the
practical education of students and professionals like min-
ing engineers, geologists, and mine surveyors. At the same
time, more than 30 national and international collaborative
research projects with various scientific and industrial part-
ners are carried out in the underground space.
The initial objective was to identify an area that would
be suitable for the project, in which experiments pertain-
ing to ventilation and deformation could be conducted
and fiber-optic sensing cables could be installed at the
floor and roof of the drift. This would enable the monitor-
ing of changes in rock deformation and temperature. The
selected part of the mine is an approximately 60 m long
drift around 140 m below the surface, that connects four
chambers. This area can only be reached via two raises from
a lower level, whereby only one of these accesses has a lad-
der, while the other access is intended for material transport
via winches. The area is mostly isolated from the rest of
the mine workings, allowing the conditions in the drift to
be well controlled, especially in terms of temperature and
ventilation. To monitor possible changes in ventilation, the
air flow will be measured using ultrasonic flowmeters that
are positioned at various points along the drift. These sen-
sors are easy to automate, can measure the air flow over the
entire cross-section and are already tried, tested and safe for
mining applications [4], [5].
To generate data for the geomechanical and geometri-
cal models, three test rigs will be installed in three different
chambers, to induce measurable deformations which will
primarily be observed by fiber-optic sensing cables.
In the first chamber, a flexible arch support is to be
installed maintaining a distance from direct contact with
the rock. Instead, hydraulic cylinders will be placed between
the arch and the surrounding chamber, with the objective of
exerting pressure on specific points of the support structure.
In the second chamber, a hydraulic cylinder will be
employed to transfer the load orthogonally onto the rock.
The resulting displacement will be recorded with fiber-
optic sensing cables on the inside of the arch and the along
the walls, respectively.
In the third chamber, fiber-optic sensing cables will be
inserted and cemented into the rock along rock bolts and
inside four boreholes arranged around each of the bolts.
The rock bolts will then be subjected to tensile loading,
similar to a rock bolt pull out test. Any deformations that
occur in the rock bolt as well as the surrounding concrete
and rock will subsequently be measured.
Monitoring Stress and Temperature
Fiber-optic sensing cables were selected because they are
widely applied in general and specifically when focusing
on underground geotechnical structures. They have advan-
tages over conventional electrical (wired or wireless) sen-
sors including their robustness against harsh environments
and they are long-term stable and chemically inert. Equally,
they are immune against electric fields, do not require elec-
tric power at the sensing position and have no impact on
electric fields themselves.
These sensors are used for distributed fiber-optic sens-
ing (DFOS). DFOS exploits different backscattering phe-
nomena in optical fibers to provide spatially resolved and
continuous profiles of various physical quantities along
their length [7]. In the context of MOVIE project, the
focus of fiber-optic sensing is on Brillouin scattering, e.g.,
[8], that allows truly distributed measurements of strain
and temperature along an optical sensing fiber loop. It has
the exploration of ever deeper ore deposits faces challenges
that require solutions such as the development of advanced
ventilation systems and geotechnical techniques to stabilize
underground structures to name only a few. In order to
conceptualize, design, construct, and work safely in under-
ground structures, it is imperative to be able to simulate
different scenarios in models. A digital twin is well-suited to
coupling different inputs, e.g., physical parameters, partly
based on real-time data, to simulate scenarios that could
occur in natural underground spaces.
Therefore, the MOVIE project aims to combine four
models, namely geological, geomechanical, geometrical
and ventilation, to create an artificial intelligence (AI)-
supported coupled model in which physical parameters
and boundary conditions can be changed to visualize the
effects. In virtual reality, the underground space can be
experienced and different parameters can be changed in real
time. This digital twin is based on an underground labora-
tory located in a former silver mine in Germany. Model
parameters are obtained from measurements in the under-
ground laboratory using fiber-optic sensing cables to moni-
tor temperature changes and the deformation induced in
different experimental setups.
METHODS
The Natural Lab: Research and Educational Mine
“Forschungs- und Lehrbergwerk Reiche Zeche”
The mine used for the construction of the underground
laboratory is the “Forschungs- und Lehrbergwerk (FLB)
Reiche Zeche” at TU Bergakademie Freiberg (TUBAF)
in Germany, part of the former silver/lead/zinc mine
“Himmelfahrt Fundgrube,” whose beginnings date back
to the 13th century [3]. Today, the mine is used in the
practical education of students and professionals like min-
ing engineers, geologists, and mine surveyors. At the same
time, more than 30 national and international collaborative
research projects with various scientific and industrial part-
ners are carried out in the underground space.
The initial objective was to identify an area that would
be suitable for the project, in which experiments pertain-
ing to ventilation and deformation could be conducted
and fiber-optic sensing cables could be installed at the
floor and roof of the drift. This would enable the monitor-
ing of changes in rock deformation and temperature. The
selected part of the mine is an approximately 60 m long
drift around 140 m below the surface, that connects four
chambers. This area can only be reached via two raises from
a lower level, whereby only one of these accesses has a lad-
der, while the other access is intended for material transport
via winches. The area is mostly isolated from the rest of
the mine workings, allowing the conditions in the drift to
be well controlled, especially in terms of temperature and
ventilation. To monitor possible changes in ventilation, the
air flow will be measured using ultrasonic flowmeters that
are positioned at various points along the drift. These sen-
sors are easy to automate, can measure the air flow over the
entire cross-section and are already tried, tested and safe for
mining applications [4], [5].
To generate data for the geomechanical and geometri-
cal models, three test rigs will be installed in three different
chambers, to induce measurable deformations which will
primarily be observed by fiber-optic sensing cables.
In the first chamber, a flexible arch support is to be
installed maintaining a distance from direct contact with
the rock. Instead, hydraulic cylinders will be placed between
the arch and the surrounding chamber, with the objective of
exerting pressure on specific points of the support structure.
In the second chamber, a hydraulic cylinder will be
employed to transfer the load orthogonally onto the rock.
The resulting displacement will be recorded with fiber-
optic sensing cables on the inside of the arch and the along
the walls, respectively.
In the third chamber, fiber-optic sensing cables will be
inserted and cemented into the rock along rock bolts and
inside four boreholes arranged around each of the bolts.
The rock bolts will then be subjected to tensile loading,
similar to a rock bolt pull out test. Any deformations that
occur in the rock bolt as well as the surrounding concrete
and rock will subsequently be measured.
Monitoring Stress and Temperature
Fiber-optic sensing cables were selected because they are
widely applied in general and specifically when focusing
on underground geotechnical structures. They have advan-
tages over conventional electrical (wired or wireless) sen-
sors including their robustness against harsh environments
and they are long-term stable and chemically inert. Equally,
they are immune against electric fields, do not require elec-
tric power at the sensing position and have no impact on
electric fields themselves.
These sensors are used for distributed fiber-optic sens-
ing (DFOS). DFOS exploits different backscattering phe-
nomena in optical fibers to provide spatially resolved and
continuous profiles of various physical quantities along
their length [7]. In the context of MOVIE project, the
focus of fiber-optic sensing is on Brillouin scattering, e.g.,
[8], that allows truly distributed measurements of strain
and temperature along an optical sensing fiber loop. It has