Numerical Simulation on Stability Development of Geogrid Reinforced Widening Embankment with Rigid Retaining Wall

Rigid retaining walls are widely used in highway widening embankments in mountainous regions. To interpret the dynamic development law and mechanics of geogrid reinforced widening embankment with the rigid retaining wall in mountainous region, combined with the particularity of the rigid retaining wall, the finite element software Phase² and strength reduction method were employed to analyse the stability of geogrid reinforced highway widening embankment in such regions. The interactions between soil and structure were introduced in the established numerical model. The dynamic development law of the mechanical response of the filling, geogrid and filling-geogrid interface, and their influences upon the embankment stability were also discussed. The findings regarding the reinforcement effect obtained from the numerical simulation were verified macroscopically using the geotechnical centrifuge model test results. The results showed that the embankment surface differential settlement was reduced by 47.1%, the maximum wall extraversion was reduced by 65.4%, and the embankment stability factor was increased by 12.8% with the geogrid reinforcement. With the increase in the shear reduction factor, the joint elements between the filling and the geogrid failed (slipped), but this slip was not responsible for the failure of the subgrade. Thus, the axial tension decreased suddenly owing to the failure of the geogrid in the upper layer, which was located outside the edge of the balancing platform. The tensile failure of the geogrid induced the instability and failure of widening embankment.