Distributed Fiber-Optic Sensing for Strain and Temperature Monitoring in an Underground Mine to Enable Digital Twin Integration

The aim of this study is to assess the potential of distributed fiber-optic sensors for measuring strain and temperature in order to monitor the structural integrity of underground mining drifts and chambers. The work is conducted within the framework of the project “Model coupling in the context of a virtual underground laboratory and its development process” (MOVIE). The overall MOVIE project aim is intended to support the creation of a digital twin, thereby improving safety and operational efficiency through enhanced digital planning across various mining environments. Time-dependent, spatially distributed temperature and rock deformation data will be recorded along fiber-optic sensing cables. These measurements will serve as boundary conditions for integrated geometrical and geomechanical models of the drift and chambers. In the initial phase, a 60-meter-long drift is instrumented using fiber-optic Brillouin-based Distributed Temperature and Strain Sensing (DTSS). Based on laboratory tests and considering the specific environmental conditions of the subsurface mine, i.e., ambient temperature variations, surface roughness, dust, and humidity, the optimal adhesive bonding materials and technique for direct cable installation on gneiss host rock was identified and successfully implemented. Following the initial monitoring setup, further experimental investigations are planned, including the monitoring of induced deformations in yielding arch support, rock bolts and the rock in contact with a hydraulic prop. The drift geometry and the spatial location of the fiber-optic cables within the drift are given by a 3D point cloud. Therefore, a 3D point cloud was captured after the fiber-optic cable installation using a high-end mobile mapping SLAM platform geo-referenced in a project-based coordinate frame. The locations of the geo-referenced fiber-optic cables will be correlated with the acquired DTSS measurements along the fiber-optic sensing cables. Ultimately, the meshed 3D point cloud will serve as foundational input for the combined geometrical and geomechanical model, forming the basis for a virtual reality-compatible digital twin enriched with real-time sensor data.