Rock anchor testing on sandstone from the Botucatu Formation, Paraná River Basin, Brazil: Insights for climbing safety procedures at the Corumbataí Geopark Project

Abstract

The Corumbataí Geopark Project, located in São Paulo state, southeast Brazil, features valuable geosites that represent Earth's heritage and attract visitors with geoturism activities such as climbing. Rock anchors are crucial for ensuring climbers' safety in case of falls. This study reveals that the load capacity performance of expansion rock anchors is influenced by the applied torque, the physical-mechanical properties of the rock, and the weathering-induced strength degradation over time. The sandstone of Botucatu Formation, the predominant lithotype at these geosites, was assessed through petrographic analysis, non-destructive testing, physical and mechanical assessments, and pull-out tests of the anchors. Our findings indicate that the sandstone generally meets the geotechnical properties requirements for load capacities outlined in international climbing guidelines, a threshold of 80 MPa is recommended for effective rock anchor performance. However, prolonged exposure leads to rock degradation, compromising safety. Consequently, anchors should not be used in weathered rock and regular maintenance is strong recommended for climbing safety, approximately every 6 six years. This study provides a novel approach to characterizing rock-anchor interactions, supporting the development of effective management plans for outdoor activities.