# Development of an Automatic Rock Mass Classification System Using Digital Tunnel Face Mapping
## 3 Automated Rock Quality Classification Using Digital Tunnel Face Mapping  
### Digital Tunnel Face Mapping  
The ventilation and installation of support systems must be executed promptly following blasting operations, which imposes considerable constraints on the temporal and spatial flexibility of tunnel face mapping. Hence, there is a pressing need for efficient methodologies in this context. The digital tunnel mapping software v. 1.0 developed in this study significantly reduces the time required for tunnel face mapping and reliable rock mass quality evaluation. This is achieved by enabling rapid image capture, allowing subsequent analysis to be conducted remotely from a safe location, thereby minimising interference with ongoing construction activities. Captured images facilitate the extraction of crucial geological information, including the distribution of rock masses classified by strength and groundwater outflow characteristics, as well as the density, spacing, length, roughness, and infill materials of discontinuities. Additionally, the degree of weathering of adjacent rock masses and the strike and dip directions of the discontinuities relative to the excavation direction can be derived from the images to automate the assignment of rock quality ratings. In scenarios where Internet connectivity is unavailable, a mobile application designed for tablets and smartphones can be used to capture photos, conduct digital mapping at each excavation face, and complete rock quality assessments. These data can be temporarily stored in the internal memory of the device until they can be uploaded to a central server when an Internet connection becomes available. Figure 6 illustrates the overall configuration of the system, showcasing both the mobile application and web-based versions developed for this study. Figure 7 provides a detailed diagram of the system architecture. Additionally, Table 4 enumerates the hardware components integral to the tunnel digital mapping system, whereas Figures 8-10 present the main menu, face mapping methodologies, and detailed features of the digital mapping system based on image data, respectively. Figure 8 presents the main interface of the mobile digital mapping system developed in this study. Upon loading an image of the tunnel surface, the dimensions are adjusted to correspond with the sketched tunnel image file. A pull-down menu facilitates the input of various parameters, including rock quality, joint characteristics, and groundwater conditions. Figure 6: System configuration for the tunnel digital face mapping. Figure 8: Main screen of the tunnel digital face mapping system. Figure 7: The system diagram for the tunnel digital face mapping. Figure 9: Input window of the joint properties. Figure 9 illustrates a pop-up window that enables users to input critical geometric characteristics of the joint orientations, as well as spacing and length. This feature allows the joint surface properties to be comprehensively described, which is essential for accurate geological assessments. Since it is impossible to estimate the strike and dip direction based solely on photographic images, the strike and dip direction of joints should be measured using devices such as a clinometer, and then the user should input those values to the mapping screen. A pop-up window displaying photographs of seven representative rock types of granite, sedimentary rock, and metamorphic rock is presented in Figure 10. This visual reference assists users in accurately identifying and specifying the rock type encountered during mapping. Figure 11 delineates the strength characteristics of the rock alongside the properties of the joints. Additionally, the groundwater condition was categorised into distinct areas, with the user interface designed to represent these conditions across five stages, ranging from dry to flowing states. This structured representation enhances the clarity and usability of the geological data collected using the mapping system.