Abstract: This paper studied highway-bridge abutment-backfill stability by the upper bound theorems of plasticity. Firstly, slip model of groundsill and backfill was decided according to centrifuge test and numerical calculation results. Secondly, the velocity field was determined based on the conditions of kinematic admissibility. Finally, to seek the least upper bound and calculate the soil pressure and the critic height, energy equilibrium theorems and programming resolutions were employed. It is pointed that groundsill and backfill material properties and reinforcement effect on abutment backfill stability markedly. The results indicate that increasing groundsill and backfill material strength, using light backfill material, dense and high strength reinforcing are propitious to backfill stability.

Key words: abutment-backfill, limit analyses, upper-bound theorems, velocity field, energy equilibrium;