Surface Settlements of the Edmonton NLRT Twin Tunnel Construction

D Elwood

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: INFRASTRUCTURE - IV Pipelines & Tunnels

ABSTRACT: The City of Edmonton has recently completed the construction of the North Light Rail Transit (LRT) extension. As part of the LRT expansion, twin, 6.5 m diameter tunnels were constructed. The twin tunnels were each approximately 350 m in length and passed through all of the overburden materials typical to the City of Edmonton. This paper will discuss the performance of the ground and the surface monitoring results measured during the tunnel construction. The monitoring data demonstrates that the surface settlements appear to near the lower end of expected responses of a tunnel constructed within a cohesive soil. The observed structure of the till appears to have controlled the extent of the surface settlements by limiting the overall width of the settlement trough. This resulted in a steeper than expected settlement trough that was contained primarily within one tunnel diameter away from the tunnel springlines. Additionally, ground movements were assessed based on settlement monitoring ahead of the tunnel face and fitted with predictive models to determine the possible impact on nearby buried infrastructure.

RÉSUMÉ: La Ville d'Edmonton a récemment terminé la construction de l'extension North Light Rail Transit (LRT). Dans le cadre de l'expansion du LRT, twin, 6,5 m de diamètre tunnels ont été construits. Les tunnels jumeaux ont chacun environ 350 m de longueur et passé à travers tous les morts-terrains typiques de la ville d'Edmonton. Cet article discutera de la performance du sol et les résultats de la surveillance de surface mesurés pendant la construction du tunnel. Les données de surveillance démontre que les colonies de surface semblent près de l'extrémité inférieure des réponses attendues d'un tunnel construit dans un sol cohérent. La structure observée de la caisse semble avoir contrôlé l'étendue des colonies de surface en limitant la largeur totale de la cuve de règlement. Cela a entraîné une plus forte dépression de règlement que prévu qui était contenue essentiellement dans un diamètre du tunnel à l'écart des springlines du tunnel. En outre, les mouvements de terrain ont été évalués en fonction de suivi de règlement devant la face du tunnel et équipés de modèles prédictifs afin de déterminer l'impact possible sur les infrastructures à proximité enterré.

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Cite this article:
D Elwood (2016) Surface Settlements of the Edmonton NLRT Twin Tunnel Construction in GEO2016. Ottawa, Ontario: Canadian Geotechnical Society.

@article{3853_0725144553,author = D Elwood,title = Surface Settlements of the Edmonton NLRT Twin Tunnel Construction,year = 2016}