Time-dependent pullout behavior of glass fiber reinforced polymer (GFRP) soil nail in sand

Cheng-Cheng Zhang 1, Hong-Hu Zhu 1, Qiang Xu 2, Bin Shi 1, and Guo-Xiong Mei 3

1. School of Earth Sciences and Engineering, Nanjing University, Nanjing, China.

2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu, China.

3. College of Transportation Science and Engineering, Nanjing Tech University, Nanjing, China.

Corresponding author: Hong-Hu Zhu

Can. Geotech. J. 52: 1–11 (2015) dx.doi.org/10.1139/cgj-2013-0381

Abstract: Glass fiber reinforced polymer (GFRP) materials are gaining increasing use in geotechnical engineering applications in recent years. The long-term performance of reinforced geostructures may be influenced by the rheological properties of GFRP soil nails or anchors. However, a clear understanding of this effect is lacking. This work aims to investigate the interaction between GFRP soil nail and sand under pullout conditions considering the time-dependent effect. A time-dependent model was proposed to describe the load–deformation characteristics of a GFRP soil nail during pullout. Laboratory pullout tests were performed using a load-controlled pullout apparatus to verify the effectiveness of the proposed model. Quasi-distributed fiber Bragg grating (FBG) optical fiber sensors were adhered on the pre-grooved GFRP soil nail to capture the variations of axial strain during testing. The test results are presented, interpreted, and discussed. It is shown that there is good agreement between the simulation results and the experimental data under low stress levels. Additionally, the impacts of model parameters on the predicted time-dependent pullout behavior of a GFRP soil nail were examined through parametric studies. The results indicate that the distributions of tensile force and GFRP–sand interfacial shear stress along the nail length are highly time dependent. The creep displacement of a GFRP soil nail is significantly influenced by the rheological parameters of the proposed model. 

Key words: glass fiber reinforced polymer (GFRP), soil nail, pullout, rheology, fiber Bragg grating (FBG).

Résumé : Les matériaux en polymère renforcé a` la fibre de verre (PRFV) sont de plus en plus utilisés en ingénierie géotechnique depuis quelques années. La performance a` long terme des géostructures renforcées peut être influencée par les propriétés rhéologiques des ancrages ou clous d’ancrage au sol en PRFV. Cependant, il reste a` comprendre de manière précise les effets de ces propriétés. La présente étude a pour but d’analyser les interactions entre un clou d’ancrage en PRFV et du sable sous l’effet de l’arrachement en tenant compte du facteur temps. Un modèle dépendant du temps a été proposé pour décrire les caractéristiques du couple charge-déformation d’un clou d’ancrage en PRFV lors d’un arrachement. Des essais d’arrachement ont été effectués en laboratoire au moyen d’un dispositif d’arrachement a` contrôle de charge afin de vérifier l’efficacité du modèle proposé. Des capteurs a` fibres optiques a` réseaux de Bragg (« FBG ») quasi distribués ont été fixés au clou d’ancrage en PRFV préfileté pour mesurer les variations de contrainte axiale durant les essais. Les résultats des essais sont présentés, interprétés et analysés dans le présent article. On montre qu’il y a une bonne concordance entre les essais de simulation et les données expérimentales pour des niveaux faibles de contraintes. En outre, on s’est intéressé, par le biais d’études paramétriques, a`l’influence des paramètres de modèle sur le l’arrachement prédit et dépendant du temps du clou d’ancrage en PRFV. Les résultats montrent que les distributions de l’effort de traction et de la contrainte de cisaillement a` l’interface PRFV–sable sur toute la longueur du clou sont largement fonction du temps. Le déplacement progressif du clou en PRFV dépend beaucoup des paramètres rhéologiques du modèle proposé. [Traduit par la Rédaction]

Mots-clés : polymère renforcé a` la fibre de verre (PRFV), clou d’ancrage au sol, arrachement, rhéologie, réseaux de Bragg (« FBG »).


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