Abstract
This doctoral research focuses on the stabilisation of weak rock formations using Glass Fibre Reinforced Polymer (GFRP) anchors, specifically addressing geo-mechanical challenges in soft rocks like calcarenite, tuff, and gypsum. The aim was to develop and validate an innovative reinforcement system that preserves both structural integrity and aesthetic value, particularly in culturally significant areas.The study began with an extensive literature review to identify existing stabilisation techniques, highlighting the limitations of traditional steel anchors due to corrosion and performance issues in aggressive environments. GFRP bars, known for their high corrosion resistance, light weight, and mechanical strength, were identified as a promising alternative.
Comprehensive laboratory tests, including uniaxial, triaxial, and indirect tensile tests, were conducted to characterise the mechanical properties of the three rock types used in the study. Also the grout materials and the GFRP bars used in the experiential campaign where characterised through standard element tests. Material characterisation was followed by the development of a bespoke pull-out testing device to investigate GFRP-rock interaction in the lab. This testing device, specifically designed for soft rocks, allowed for accurate load-displacement measurements and provided insights into the bond strength between GFRP anchors and various grout materials.
Field tests were then conducted in three sites characterised by soft rock formations. Hereto a custom-designed equipment for in-situ pull-out tests was developed to ensure precise axial alignment and minimal interaction between reaction plates and bar-rock interface during the tests. To aid the design, Finite Element Method (FEM) simulations were used. The field test results demonstrated that GFRP anchors offer comparable or superior performance to steel anchors in terms of strength and ductility. Surprisingly, despite the GFRP is a more fragile material, the GFRP-rock system was found to be able to accumulate more displacements and higher failure loads with respect to an equivalent sized steel reinforcement.
A simple analytical tool to predict GFRP bar pullout response was developed and validated in a real case study also described in this work. For the latter FEM analyses were used to design a GFRP bar reinforcement of an unstable partition wall in an anthropic cavity in Calcarenite.
Overall, this research shows that GFRP anchors can provide a reliable, long-term solution for stabilizing soft rock formations, contributing both to infrastructure safety and heritage preservation.
| Date of Award | 2025 |
|---|---|
| Original language | English |
| Awarding Institution |
|
| Supervisor | Matteo Ciantia (Supervisor) |