Analysis of soil settlement behind bridge abutments

The roughness of the transition between the roadway and the bridge is a well-known issue. As soil underneath the approach slab settles, bumps could develop at the ends of the bridge when abrupt changes in the slope of the approach slab occur. Proper design of the approach slab would require accurate prediction of the soil settlement profile of the embankment fill behind bridge abutments. This study is aimed at developing empirical relationships to evaluate the settlement of the embankment soil without any mitigation measures. A parametric study, using finite element analyses, was performed to evaluate the soil/approach slab settlement under various soil/abutment conditions and parameters. As a result, empirical relationships are proposed (using a logistic function) that relate various soil and abutment parameters to the longitudinal soil settlement profile. The proposed equations would be beneficial in predicting the long-term settlement of the soil behind abutments, and for planning mitigation measures for any bumps that may develop at bridge ends.