Evaluation of Tensile Strength Testing of Fiberglass and Steel Rebar in Nailing of Tunnel Excavation Fronts in Soil Masses 

Gustavo Pagliari Valerio dos Santos, Leonardo Demetrio, Maria Júlia Ibidi Limongi França, Fernando Luiz Lavoie, and Daniel Kashiwamura Scheffer 

Instituto Mauá de Tecnologia, São Caetano do Sul, Brazil 

Abstract: This work presents a study of the behavior of fiberglass in its application as a reinforcement element in the containment of soil masses in the form of rebar and a comparison with respect to steel for the same application. It was designed from the results of tensile strength tests performed with fiberglass and steel rebar and the development of a statistical study to increase the accuracy of the results, obtaining more refined information about the actual conditions of differentiation and a concise determination of the presented advantages of one material with respect to the other as to its tensile strength. It would be possible to perform the statistical study using the Normal (Gauss curve) standard, which considers the mean and standard deviation values as the global values for both materials. However, due to the reduced number of available specimens, the t-Student test standard was used for executing a comparative analysis between the groups. This is based on the mean and standard deviation of the results obtained for the samples to compare the average tensile strength of both materials globally. The results allowed affirming that the fiberglass rebar presents tensile strength at rupture with statistically significant superiority in relation to the steel rebar. 

Key words: fiberglass, nailed soil, rebar, steel, tensile strength tests