# An Established Theory of Digital Twin Model for Tunnel Construction Safety Assessment
## 5 Case Study  
### Modeling Accuracy and Content  
According to the rules described in Section 4.1.1, the construction elements of a tunnel construction process are classified and analyzed according to men, machines, materials and environment. What's more, the black, gray and white levels are classified according to their different impacts on construction safety and available data. In this study, RFID tags are used as the main technology to store information of various construction elements. The information stored in RFID tags can be updated and edited in real time. Therefore, we can choose the appropriate time point to change the status information of construction elements. Before construction, the specific information of construction elements is gathered by scanning the electronic tags on the components. All kinds of structural information are monitored by various sensors, and the data collection interval is two seconds. Figure 7: The structure of LSTM. In the construction process, human safety is a key consideration in safety management, and human status has an important impact on the overall safety of the construction. Therefore, it is necessary to collect information that is as detailed as possible on construction personnel, including age, type of work, working years, working status, location, etc. However, because geometric information of construction personnel has little impact on the construction structure, there is no need to establish a geometric model; consequently, the model accuracy of construction personnel is at the gray-box level. The model expression of construction personnel is as follows: \(PI_{1}=\{\)[SG001, M, Constructor, 35, 10], [228.2, 202.3, \(-\)11], 78]. The specific meaning is {[Job number, male, type of work, age, working years], location coordinate, heart rate]. The coordinate origin of the location coordinate is a point on the site elevation of the Project Department of the construction bid section. The status of construction machinery and equipment has an essential impact on the progress and quality of the construction project. Therefore, it is necessary to ensure that the construction machinery and equipment maintain normal working conditions. However, since much construction equipment does not belong to the project itself, it is not necessary to build a geometric model, and the gray-box level is sufficient. Manage relevant data on construction equipment during construction. As described in Section 4.2 above, RFID is filled with pertinent information on mechanical equipment. Firstly, input the mechanical equipment's basic information and working status information into the RFID tag and paste RFID tags onto the corresponding equipment. Before construction, the RFID handheld terminal can scan the electronic tags on the equipment to learn the functionality of mechanical equipment. Meanwhile, the information for the working status of the equipment can be changed from \"idle\" to \"working\". Taking the segment installation machine during shield tunneling as an example, its model expression formula is \(CE_{1}=\{\)[CREC010, segment installation machine, Segment assembly, 120 kN@130 bar, 320 kNm@210 bar, 400 kNm@260 bar, 6 degrees of freedom, ring gear type, mechanical gripping, Hydraulic drive], working, [28 \({}^{\circ}\)C, 580 MPa, 300 MPa, 0.3 m, 0.7 rpm]. The specific meaning is {[ID code corresponding to the machine model, equipment type, function, rated lifting capacity, rotating torque, static torque, type, driving mode, and other core parameters], operating state of the equipment in working, [operating temperature, contact stress, gear bending stress, displacement, rotation speed]). The materials are the basis of the construction structure. In this paper, the structural components are the basic units of construction material modeling. The BIM model containing the construction information such as the material type, strength, and location is established as the constituent elements of the geometric model of the construction structure.