Mechanical Behaviour of TSL for Concrete Tunnel Linings

Taesang Ahn, K.Y. Lo, Sean Hinchberger

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Infrastructure

ABSTRACT: This paper presents the results of load tests on tunnel lining segments. The full-scale tests consisted of five flexural tests of precast reinforced concrete segments with and without the Thin Spray-On Liner (TSL) coating. Evaluation of the TSL effect on load-carrying capacity was made among these segments. Additionally, three dimensional numerical analyses using ABAQUS were performed with predetermined parameters from uniaxial compressive tests on actual concrete used for casting these segments and tensile strength tests on the TSL. The numerical results were then compared to the measured results in load-displacement and load-strain at strategic locations. On the basis of the results from the tests, the TSL coating increased the maximum load capacity by approximately 10% when compared to the load capacity on concrete segments without the TSL coating. The calculated and measured displacements have good agreement while satisfactory agreement between the calculated and measured strains was obtained in the middle of the segments. However, there was some discrepancy between predicted and measured strains at the locations farther away from the mid-section. RÉSUMÉ Cet article présente les résultats de tests de charge sur tunnel voussoirs. Les essais à grande échelle étaient composés de cinq essais de flexion de béton préfabriqué renforcé segments de béton avec et sans le mince à vaporiser Liner (TSL) de revêtement. Evaluation de l'effet de TSL sur la capacité de charge a été faite entre ces segments. En outre, trois analyses numériques dimensions en utilisant ABAQUS ont été réalisées avec des paramètres prédéterminés des essais de compression uniaxiale sur le béton réel utilisées pour la coulée de ces segments et des tests de résistance à la traction sur la TSL. Les résultats numériques ont ensuite été comparés à des résultats de mesure de la charge-déplacement et de la charge-déformation à des emplacements stratégiques. Sur la base des résultats des tests, la couche de TSL a augmenté la capacité de charge maximale d'environ 10% par rapport à la capacité de charge sur les segments en béton sans le revêtement de TSL. Les déplacements calculés et mesurés ont une bonne entente en accord satisfaisant entre les souches calculées et mesurées a été obtenu dans le milieu des segments. Cependant, il y avait une différence entre les souches prédites et mesurées à des endroits plus éloignés de la section du milieu. 1 INTRODUCTION Precast concrete segmental tunnel linings are generally considered to be durable and require minimal maintenance. However, serious maintenance problems can be caused by earthquakes, leakage through lining joints, increasing traffic in tunnels, or chemical attack from the groundwater or environmental pollution. Damage on concrete liner caused by earthquakes or concrete degradation due to chemical attack can decrease joint stiffness and reduce the load-carrying capacity of tunnel linings. The factor of safety of a tunnel lining may gradually decrease as time passes due to these effects and thus, it is important to consider the reinforcing of degraded concrete liners (He and Wu, 2005). A method for reinforcing degraded concrete linings discussed in this paper is to use Thin Spray-On liners (TSLs). TSLs are used as a preliminary excavated surface stabilizer of tunnels or shafts in the mining and tunnelling industries. For subway tunnel linings, a properly designed TSL may be used to seal the inner tunnel surface, as other conventional coatings such as shotcrete and steel or mineral board cannot be applied due to space limitations for existing tunnels. The objectives of this study are to: i) evaluate the flexural strength of precast reinforced concrete tunnel lining segments similar to those used to construct subway tunnels during the 1970s, ii) investigate the effect of a TSL on the load carrying capacity of the linings subject to the same loading, iii) perform a non-linear elastoplastic finite element analyses using ABAQUS to simulate the structural response of the TSL coated and uncoated precast reinforce concrete tunnel lining segments, iv) investigate the effect of the TSL on the crack development and propagation during the tests. 2 THE THIN SPRAY-ON LINER (TSL) Thin Spray-On Liners are widely used in the mining industry as an initial stabilizing layer on excavated rock surface. Various TSLs are currently being developed and

RÉSUMÉ: echanical Behaviour of TSL for Concrete Tunnel

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Cite this article:
Taesang Ahn; K.Y. Lo; Sean Hinchberger (2014) Mechanical Behaviour of TSL for Concrete Tunnel Linings in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper410,author = Taesang Ahn; K.Y. Lo; Sean Hinchberger,title = Mechanical Behaviour of TSL for Concrete Tunnel Linings,year = 2014}