Mitigación del peligro de desprendimientos en terrenos volcánicos mediante análisis estadístico. El caso de Gran Canaria

Résumé

Rockfalls on transport infrastructures are a serious hazard to users and many resources are invested in rock slope mainte- nance, stabilization, and protective measures. In volcanic territories, the risk of rock instabilities and rockfalls is very high due to the rugged natural slopes and origin of rock masses. With the aim of determining the influence of the geometric and material-related properties affecting rockfall motion and the effectiveness of catchment area design criteria, this preliminary study has been carried out in Gran Canaria and applies a back-analysis considering 11 torrential basins with a different slope configurations, 4 types of materials and 4 size and shape combinations of falling rocks. A statistical analysis of the rock stop-distances was performed. Results show that density, hardness, roundness and size are material properties directly corre- lated with the rockfall stop-distance. However, block accumulation distribution differs with the rock hardness. Furthermore, a practical maps with a block accumulation percentage are proposed for the local infrastructure planning and design tasks. These maps offer a hazard index associated with the current design of existing roads based on the relationship between the optimal stopping distance and the accumulated percentage retained along the path, complying with specific retention require- ments. These maps offer the dangerous associated with the current design of existing roads depending on the relation between the optimal stop-distance and the cumulative percentage retained along the trajectory, complying with specific retention requirements. This index allows validating the suitability of existing ditches and improving non-structural defense measures with reduced environmental impact and cost in volcanic territories.