Beishan exploration tunnel surrounding rock discontinuity identification based on structure from motion photogrammetry technology

The Beishan Exploration Tunnel (BET) is a facility built to develop technologies associated with the safety of China's first high‐level radioactive nuclear waste(HLW) disposal. The surrounding rock discontinuity identification is a key research topic in BET, which could provide essential geological data for future HLW disposal stability and integrity research. This article presents the rock discontinuity identification research progress in BET based on Structure from Motion (SfM) photogrammetry technology. The discontinuity identification algorithm is improved by introducing the region‐growing algorithm to optimize the candidate subplane. This algorithm automatically picks the seed, avoids human intervention, and thus increases the work efficiency of the discontinuity identification. The FCM method is improved by embedding with the CFSFDP algorithm in the discontinuity sets grouping. The CFSFDP algorithm coincides well with the Fisher distribution of discontinuity orientations, which is suitable for the Beishan situation. A parallel scheme is used when implementing the method, which accelerates the discontinuity calculation. This improved rock discontinuity identification method was tested on a slope above the BET and applied in the BET. The discontinuity identification results were compared with the results from the manual field measurement and the open‐source software DSE. The results show that the improved discontinuity identification method obtains reliable discontinuity data and costs less time and human workload than the other two methods. The surrounding rock discontinuity identification research provides a powerful tool for the Beishan HLW disposal geological investigation.