# Digital Twin-Driven Stability Optimization Framework for Large Underground Caverns
## 3 Practical Implementation and Case Study
### Digital Twin Application for Monitoring and Stability Assessment
#### 3.2.4 BIM-Based Design and Construction Simulation  
The BIM-based design and construction simulation are critical components of the DT framework, enabling the detailed digital representation of the underground cavern's geometric and semantic attributes. A BIM-driven digital framework was developed to simulate the structural behavior, excavation process, and rock support system, ensuring that all construction phases were optimized for safety and efficiency. The development of BIM-based digital design starts from Step 2 in the BIM-based virtual environment. Then, in this step, as the design goes towards finalization, the creation of a parametric geometric model, which provides a comprehensive three-dimensional visualization of all structural components, including excavation geometry, phased excavation plans, and geotechnical data, is performed. These models are updated in case of any changes required during  
Figure 8: Three-dimensional finite element analysis (FEM). (**a**) Overview of BIM-based 3D generation of mesh of powerhouse; (**b**) initial stress condition (\(\sigma_{1}\)) at powerhouse; (**c**) total shear strain of powerhouse floor (577 m); (**d**) deformation pattern during stage 4 of excavation.  
the construction phase based on any necessary changes for the optimal stability of the underground cavern.  
The BIM model was designed by using Industry Foundation Classes (IFC)-compliant data structures, ensuring interoperability across different software platforms. Figure 9a illustrates a Building Information Modeling (BIM)-based excavation plan, detailing the sequential excavation process using a heading and bending approach. The model incorporated key components such as the geometric representation of the cavern, rock mass classification, and excavation sequencing as already defined in the Methodology section. Structural components, including shotcrete layers, rock bolts, and anchors were embedded in the model (Figure 9b). Additionally, the model included the layout of monitoring instruments, allowing real-time deformation data from sensors such as extensometers, load cells, and convergence arrays to be linked directly with the digital model for real-time deformation monitoring and feedback during construction and operational phases.  
A BIM-based construction simulation was carried out to analyze and optimize the excavation and rock support installation sequence. The virtual construction process, including sequential excavation modeling, was then used for the FEM simulation to simulate the excavation stages, helping us to understand stress redistribution and deformation patterns. Figure 9c showcases the finite element method (FEM) simulation of the excavation sequence, demonstrating how stress redistribution and deformation occur as different excavation stages progress. During the construction phase, the BIM model is continuously updated with as-built information, ensuring that the virtual model remains an accurate reflection of the physical structure. This real-time synchronization between the virtual  
Figure 9: BIM-based construction simulations. **(a)** Solid BIM-model showing excavation sequence with heading and bending approach; **(b)** BIM-based rock support model showing anchors, rock bolts, shotcrete, and monitoring instruments; **(c)** excavation sequence FEM analysis to simulate redistribution of stresses and deformation.  
and physical worlds allows for the continuous necessary adjustments to the rock support design or construction sequences to be made promptly based on the feedback from the monitoring instruments, ensuring that the underground cavern remains stable and safe throughout its lifecycle.