Research on Centrifugal Model Test of Bridge Abutment Backfilling

Excessive surface settlement of fill behind abutment and high lateral earth pressure acting on the abutment wall will develop abutment movement and bump at the end of the bridge. A crucial approach to solving these problems is to select a proper backfill and disposal scheme behind the abutment. The present study is aimed to examine the pressure and deformation properties of various fills behind the bridge abutment by the use of centrifuge. The experimental design follows the similitude relationship of centrifugal model test. This includes scaling of model geometry, geosynthetic reinforcement stiffness, backfill soil modulus, EPS interlayer modulus, and abutment back structure and foundation. Finally, the test results of centrifugal model are compared with the field measurement results. The achieved results indicate that the earth pressure and surface settlement of ceramsite fly ash concrete behind abutment are remarkably lower than those of other backfill, which could be preferred as backfill materials. Further, the higher compaction level of the backfill leads to a decrease in the settlement of the backfill. It is also noticed that the geogrid reinforcements result in the enhancements of the strength of the backfill and the reduction of the lateral earth pressure exerting on the back of the abutment. Additionally, the earth pressure of backfill is noticeably lessened after installing the EPS panel on the back of the abutment, and for the structure equipped with geogrid reinforcement and EPS panel, further lessening of the earth pressure is detectable. Finally, the normalized soil settlement of the pile-supported abutment is remarkably higher than that of the gravity abutment, and the deformation characteristics of backfill considerably are determined by supporting capacity of the subgrade. The present research provides a preliminary basis for decreasing the bump at the end of the bridge.