Field monitoring of earth pressures on integral bridge abutments

Integral abutment bridges have become a successful alternative to the traditional design procedure of using expansion joints to balance the thermal movements of bridge structures. However, there are many design and detailing variations, and uncertainties exist about the soil-structure interaction of the integral abutments. Therefore, field data from pressure cells installed behind the abutments of a 76 m long, two-span, pile-supported integral abutment bridge are the focus of this paper. The data on external displacements of the abutments are also reported. The applicability of using common theoretical passive earth pressure coefficients is assessed and it appears that the traditional methods of Coulomb and Rankine are not the best approach for predicting the earth pressure envelope. Additionally, over the monitoring period of three years, it was found that a definite conclusion regarding the ratcheting of lateral earth pressure could not be established for this bridge site. Finally, comparisons to earth pressures measured at other field studies indicate variability in the earth pressure distribution, magnitude, and behaviour over time, as these are dependent on several factors distinctive to each bridge site.