Investigating the Occurrence and Effects of Fragmentation: Analysis of Rockfall Videos Captured During Slope Maintenance Campaigns

Rockfall is a gravity-driven natural hazard common in mountainous areas, that poses a risk to infrastructure and human life. Understanding rockfall frequency and potential trajectories are essential for the safe design of roads and railways. This is traditionally through analysis of the slope and historical rockfall data. Fragmentation results in a spreading effect of the fragments, and alters most factors used to approximate rockfall behaviour and hazard calculations. Improved knowledge of fragmentation is vital for better protecting infrastructure in rockfall-prone areas. The focus of this research is to investigate factors influencing the occurrence of fragmentation and how fragmentation affects rockfall behaviour. Data was collected remotely due to issues with the COVID-19 pandemic. A methodology for collecting rockfall video data was developed and 218 videos from slope maintenance campaigns across the U.S. were analyzed. A fragmental video database was created, extracting 76 variables related to the slope, rockfall, and fragmentation from videos. Supplementary data (photos, notes, 3D models) is used to enhance video analysis, capturing key details such as slope conditions, slope geometry, and fragment locations. The following trends were discovered from the database analysis. Several factors were found to be associated with an increased chance of fragmentation: igneous rock type, a first impact on rock, bladed and platy rockfall shapes, rockfall exhibiting freefall, steep slopes and slopes with trees. Compact rockfalls fragmented less often than rockfall of any other initial shape. The rockfall, primary and secondary fragment shapes all seem to be influenced by the rock type, and the fragment shapes influenced by the initial rockfall shape. Most rockfalls fragmented only once, with fragment numbers showing a gap-graded pattern.

Department dc:contributor.department

Geological Sciences and Geological Engineering

Year dc:date.issued

2024

Author dc:creator

• MacPhail, Ruairidh

Advisor dc:contributor.supervisor

• Hutchinson, Jean

• Rockfall
• Rockfall Fragmentation
• Geological Hazard

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1974/33527

OAI identifier oai:identifier

oai:queensu.scholaris.ca:1974/33527