Dynamic response of tiered geogrid-reinforced soil retaining walls under traffic loading

The multi-tiered geogrid-reinforced retaining wall (GRSRW) has been widely used in road retaining projects in mountainous areas. A 1∶3 large-scaled model test is carried out to investigate the performance of a two-tiered GRSRW with the same total height. The influences of offset distance D on its foundation settlement ratio is analyzed firstly, and then under the specified offset D=0.4H₂ (H₂, the height of the lower wall), the effects of variation of amplitude and frequency of the traffic loading on the panel horizontal displacement, earth pressure, reinforcement strains, strain distribution and potential failure surface are studied comprehensively. The test results show that the settlement ratio of loading plate at the top of retaining wall and the horizontal displacement ratio of panels increase significantly at the very beginning with the increase of the number of the traffic loading, and the displacement increment gradually tends to be convergent with the further increase of cycle times. The maximum displacement occurs at the upper wall height of about 0.85H (H is the total wall height), and the distribution mode of the horizontal displacement is not affected obviously by the traffic loading. To increase the amplitude and frequency of the traffic loading can remarkably affect the strains of geogrid layers of the upper wall, and the strains of geogrid, below the toe of upper wall, of the lower wall are relatively greater. The horizontal earth pressure of the upper and lower walls is small at the top and bottom of the retaining wall, but large in the middle. The potential failure surface of the upper wall moves downward with the increase of the loading amplitude, and the failure mode of the upper wall gradually changes from local failure to deep global one. The filling process will increase the vertical stress of the lower wall near the panel to about 1.5 times the self-weight. The conclusion can provide a helpful guidance for the design and construction of tiered GRSRWs.