Use Of A Rock Filled Tyre Wall To Provide Passive Support To A Large Bridge Abutment

This paper describes the geotechnical assessments undertaken to demonstrate the global stability of an alternative abutment solution, implemented to accommodate construction of a large railway bridge for a corridor widening project.

Excavation for a crane and piling platform to facilitate installation of pier foundations and erection of the bridge superstructure resulted in the reduction of passive earth in front of piles supporting a stem wall that would eventually retain abutment fill. The construction program required backfilling of the abutment concurrent with the construction of the adjacent central pier, resulting in the implementation of a rock-filled tyre wall to restore passive support. The tyre wall, however, was closer to the abutment and significantly truncated the theoretical passive failure wedge. Geotechnical assessment of global stability was undertaken by staged analysis with finite element software. The new configuration was demonstrated to be structurally sound and geotechnically stable in both the temporary and permanent condition. This permitted the final access track to be relocated to a position that provided further economy in construction. The analytical model was also used to determine structural design actions in response to observations of wall movement during the backfilling process.

It can be noted that certain details, including project name and location, have been omitted from this paper to respect the confidentiality of affiliated parties.