Reduction of Earth Pressure and Displacement of Abutment with Reinforcement Filling

Abstract

The common method to construct expressway is construct a bridge abutment before filling embankment in China. The earth pressure acting on the abutment during filling embankment is much higher than the active earth pressure because of the rolling action of the fill. The bridge abutment and the piles under the abutment may occur significant horizontal displacement due to the higher earth pressure acting on lateral faces of abutment. The bearing capacity of the abutment piles would be reduced if the horizontal displacement is beyond a critical volume. The stress condition of the abutment piles is changed from axial compression to bending-compression. The change of the stress combination may have a negative influence to the safety of bridge abutment. The geo-grid reinforced soil can be used as filling in the abutment zone to reduce the earth pressure acting on the abutment and the horizontal displacement of the abutment. A case study has been done at two flying bridges over the Ninghuai Expressway of Jiangsu, China. This case study has analyzed the effect of geo-grid reinforced with the comparison of the earth pressure acting on the abutment and the horizontal displacement of the abutment between the abutments for having and having not geo-grid reinforcement in the filling. Test results show that the increment ratio of earth pressure on the abutment for which the filling of the embankment behind the abutment is geo-grid reinforced is 0.52 to 0.81 fold of that on the abutment for which the filling of the embankment behind the abutment is not geo-grid reinforced. The horizontal displacement of the abutment with reinforced filling is 26% to 43% less than that of the abutment with usual compacted filling.