Settlement and Horizontal Earth Pressure behind Model Integral Bridge Abutment Induced by Simulated Seasonal Temperature Change

Expansion and contraction of an integral abutment bridge cause an abutment to move toward and away from its backfill due to seasonal temperature changes, thus causing high horizontal earth pressures behind the abutment and backfill surface settlements. This paper presents the results of four model tests conducted to simulate both translational and rotational movements of abutments and investigate horizontal earth pressures behind the abutment and the backfill surface settlements. The test results showed that the translational movement of the abutment likely prevented soil ratcheting from occurring in the upper portion of the backfill due to stress adjustments in the backfill after simulated seasonal temperature changes (i.e., causing limited earth pressure increase behind the abutment). Furthermore, the existing methods used to predict the horizontal earth pressures behind the abutment overestimated the pressures at the bottom of the abutment if the translational movement of the abutment was permitted. In addition, the backfill surface settlement near the abutment, induced by the seasonal temperature changes, was a function of footing rigidity and the displacement magnitude of the abutment and continued even after 30 cycles of abutment movement.