The axial response of fully grouted rock bolts using a distributed fiber optic sensor technique

Tyler O’Connor, Bradley Forbes, Nicholas Vlachopoulos, Mark S. Diederichs

In the proceedings of: GeoSt. John's 2019: 72nd Canadian Geotechnical Conference

Session: Rock Mechanics

ABSTRACT: The primary function of rock bolts is to stabilize the weakened ground around the periphery of the tunnel by transferring the load from the weakened rock to the more stable rock deeper into the rock mass. Through the use of a fiber optic sensor technology that has been developed by the authors, axial strain along the fully grouted rock bolt can be determined at a spatial resolution of 0.65 mm. This continuous strain monitoring technique provides comprehensive and unique insight into load transfer mechanism(s). This allows for in-depth geomechanical insight with respect to the behaviour of fully grouted rock bolts with a view to optimizing the performance of such rock support elements. In particular, this paper examines the effect of embedment length based on various simulated rock grout mixtures as well as specimen/rebar sizes. This paper summarizes the methodology employed for such laboratory testing of rock bolt (rebar), and provides results for a cement-grouted sample with an embedment length of 500 mm.

RÉSUMÉ: La fonction principale des boulons est de stabiliser les sols affaibli à la périphérie dun tunnel en transférant la charge du roc affaibli au roc plus stable situé en profondeur dans la masse rocheuse. Avec e capture par fibre optique développée par les auteurs, il est possible déformation axiale le long du boulon d entièrement encastré avec une résolution spatiale de 0,65 mm. Cette technique de surveillance des déformations le long du boulon fournit, en temps réel, une vue complète et claire sur le mécanisme de transfert des charges. Cela permet de mieux comprendre le comportement géomécanique des boulons entièrement encastré en vue d'optimiser la performance de tels éléments d. de la castrement à partir de divers mélanges de mortier dans des rocs simulés, et de la taille des échantillons / barres d'armature. Cet article résume la méthodologie employée pour des essais en laboratoire de boulons (barre) et fournit les résultats obtenus pour un échantillon ciment-mortier castrement de 500 mm.

Access this article:
Canadian Geotechnical Society members can access to this article, along with all other Canadian Geotechnical Conference proceedings, in the Member Area. Conference proceedings are also available in many libraries.

Cite this article:
Tyler O’Connor; Bradley Forbes; Nicholas Vlachopoulos; Mark S. Diederichs (2019) The axial response of fully grouted rock bolts using a distributed fiber optic sensor technique in GEO2019. Ottawa, Ontario: Canadian Geotechnical Society.

@article{Geo2019Paper221,author = Tyler O’Connor; Bradley Forbes; Nicholas Vlachopoulos; Mark S. Diederichs,title = The axial response of fully grouted rock bolts using a distributed fiber optic sensor technique ,year = 2019}