Centrifuge model tests on vertical stress distribution of geosynthetics reinforced soil (GRS) abutment

Geosynthetics reinforced soil (GRS) abutment has been widely used in the construction of small to medium single-span bridges and shows good service performance in engineering projects. Vertical stress distribution plays an important role for engineering design of the GRS abutments. Three centrifugal model tests of GRS abutments were carried out to investigate the vertical stress distribution underneath the centreline of beam seat, considering the setback distance (i.e., the distance from the beam seat to the inner of the facing) and beam seat width as influencing factors. Test results indicated the measured incremental vertical stresses under the beam seat increased with increasing loads uniformly and presented "larger on the upside and smaller on the downside" along the elevation. There existed the phenomenon of stress concentration near the top of the abutment and with the increasing beam seat width, the phenomenon of stress concentration presented more obvious. However, the setback distance had little effect on the vertical stress distribution. A comparison between measured and theoretical vertical stress showed that the AASHTO method provided a better prediction of the incremental vertical stress distribution than the FHWA method under the load of 200 kPa, but with the increasing loads, these two methods significantly underestimated the incremental vertical stress.