Rockfall Feature Investigation and Kinematic Simulation Based on Nap-of-the-Object Photogrammetry and GIS Spatial Modeling

Abstract

Abstract Chaya County, as one of the important towns in the "Three Rivers Region" in southeastern Tibet, is the key target for future expansion and development. Disaster risk investigation and research are the primary task of county expansion and development. UAVs have been widely used in disaster surveys by virtue of their ability to rapidly acquire rich and diverse geospatial data. However, due to the comprehensive influence of terrain environment, GPS positioning accuracy, and image acquisition and processing methods, the positioning accuracy and resolution acquired from the 3D model and DSM data are difficult to guarantee its reliability. In this case, when interpreting rock mass characteristics, there will be limitations such as inaccurate extraction of joint and fissure information, inability to reflect rock mass surface roughness, and even incapacity to identify fine joints. Meanwhile, the resolution of terrain data will also affect the reliability of the simulation results of rockfall motion characteristics. Therefore, a new image acquisition method and modeling idea are summarized in this paper, and obtains a real-world 3D model with a positioning accuracy of less than 5 cm and DSM data with sub-centimeter resolution for a slope in the study area by this way. According to these data, a rock mass characteristic survey was completed, and a 3D numerical simulation of the potential rockfall movement characteristics was performed in GIS. At present, there are three potential rockfall areas in the study area, with a volume of about 2690m³. Affected by factors such as freeze-thaw erosion, differential weathering, faults, and unfavorable structural plane combinations, rockfall disasters may continue to occur in the future. The simulation results show that after the high-level rockfall occurs, the movement trajectory presents a diversion phenomenon, and the side of the township road is more threatened than the side of the G349 National Highway. The results of this paper have important reference value for disaster prevention and mitigation for the expansion of Chaya County, and can also provide important basic data for the research on fault activity, landform formation and evolution in Changdu and surrounding areas.