Tara Sassel

Analysing Earth Pressure Build-Up Behind Integral Bridge Abutments Using DEM

Started: October 2018

Supervisor: Prof Catherine O'Sullivan

Description of Research

Integral bridges do not have joints and bearings. In conventional bridges there is damage of the joints due to de-icing salts and accumulation of debris between the joints. This leads to a significant amount of maintenance which has to be carried out on those bridges. In integral bridges the abutment is rigidly connected to the deck. As the deck expands and contracts with temperature changes, the abutment is subjected to a cyclic movement. This movement leads to settlement of the backfill soil adjacent to the abutment and build-up of earth pressure. Currently there is no guidance in the Eurocodes on the earth pressure build up and the developing settlement throughs behind integral bridges. There are two UK guides on integral bridges. Some insight into soil behaviour has been obtained using physical centrifuge models and settlement tests. This study aims to further advance understanding using discrete element method (DEM) simulations.

In this project the use of the discrete element method (DEM) will be examined to improve the understanding of the soil behaviour adjacent to integral bridges in engineering practice. DEM considers the soil as a system of rigid particles and can simulate the particle scale interactions that lead to an overall complex behaviour. In the first stage of this research, a DEM model has been created using the PFC2D software, as illustrated here. Data from these simulations will be compared with the physical model test by Lehane (2011). Furthermore, 3D simulations of element tests will be carried out to improve the understanding of the ratcheting phenomena associated with integral bridge backfill as well as particle shape effects.