Static and seismic behavior of culverts constructed with TDA inclusion

Dahlia Hafez, Alper Turan, Hany El Naggar

In the proceedings of: GeoMontréal 2013: 66th Canadian Geotechnical Conference; 11th joint with IAH-CNC

Session: Foundations II

ABSTRACT: The province of Ontario generates about 12 million tires half of which are recycled and the rest are shipped out of province, mostly to be burned as fuel in cement factories. The recent studies have highlighted several special properties of tire derived aggregate (TDA) that can be used to address various engineering challenges. For example, TDA is compressible, light weight, has high permeability and low thermal conductivity. This study provides a series of static and seismic numerical analyses to investigate the effect of TDA inclusions as a lightweight compressible fill to reduce the static and seismic forces on culverts. The analyses were performed using the finite element program PLAXIS. Linear and nonlinear soil models were considered with different configurations of the TDA layer. Results indicated that the use of TDA inclusions above the culvert resulted in significant reductions in the forces and moments induced on the culvert under both static and seismic loads.

RÉSUMÉ: La province de l'Ontario génère environ 12 millions de pneus dont la moitié sont recyclés et le reste est expédié hors de la province, principalement à être brûlé comme combustible dans les cimenteries. Les études récentes ont mis en évidence plusieurs propriétés particulières d'agrégat dérivé du pneu (TDA) qui peut être utilisé pour traiter divers problèmes d'ingénierie. Par exemple, TDA est compressible, léger, a une perméabilité élevée et une faible conductivité thermique. Cette étude fournit une série d'analyses numériques statiques et sismiques pour étudier l'effet des inclusions TDA comme une compressible légère couche pour réduire les forces statiques et sismiques sur les ponceaux. Les analyses ont été effectuées en utilisant le PLAXIS programme des éléments finis. Modèles de sol linéaires et non linéaires ont été considérés avec différentes configurations de la couche TDA. Les résultats indiquent que l'utilisation de TDA inclusions au-dessus du ponceau a entraîné des réductions importantes dans les forces et les moments induits sur le ponceau sous les charges statiques et sismiques. 3 INTRODUCTION Conduits, such as structural culverts, are often used in highway construction under high highway and railway embankment fills. Rigid structural culverts are often used by many transportation agencies. The stresses exerted on deeply buried culverts are resisted by the culvert itself and surrounding backfill material. The applied stresses are distributed within the fill material and then transferred to the structure, where they are resisted by the strength of the structural elements. The stresses are then transferred to the founding stratum (Spangler and Handy, 1973). For conventional backfilling methods, the settlement of the embankment fill immediately above the culvert is less than the settlement of the adjacent fill. This causes a downward shearing force to act on the structure, which increases the stresses it must resist. This mechanism is referred to as negative arching (Selig, 1972, Vaslestad et al. 1993). Therefore, based on the same principle, when the relative settlement of the soil directly above the culvert is greater than the adjacent fill, the earth load on the culvert is reduced by the upward shearing forces, which is known as positive arching. This positive arching effect can be achieved through a construction method called the induced trench method (ITM). The ITM method dictates that a buried structure is to be backfilled, and well compacted, to a certain height above the structure. Then, a trench of backfill is to be opened and refilled with compressible lightweight material. Traditionally, baled hay or leaves have been used to backfill this trench. Different design approaches are used for the design of ITM type culvert installations such as Marston-Spangler Method (Marston, 1922, Spangler, 1950a,1950b) and Vaslestad Method (Valestad et al. 1993). Tire derived aggregate (TDA) is used as a light weight embankment fill, due to the fact that it is an eco-friendly alternative to other light weight fills. TDA is made from tires shredded in certain particle sizes. TDA is already used for numerous civil engineering projects due

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