Experimental study on seismic response of geogrid reinforced rigid retaining walls with saturated backfill sand

To study the seismic performance of geogrid reinforced rigid retaining walls with saturated backfill sand, large-scale shaking table test models were constructed in a large laminar shear container, which included geogrid reinforced rigid retaining walls and unreinforced soil retaining walls. The geometric similitude rules of test walls were confirmed by the Froude constant in dimensional analysis theories, which could be expressed by the shear velocity of the soil, and the similitude ratios of the other variables were deduced from the geometric similitude ratio. The shear wave velocities of the model grounds were tested using a seismic dilatometer. Considering the effects of ground motions, the seismic response of the retaining walls were investigated, along with wall accelerations, lateral displacements of walls, seismic settlements of the backfill sand surfaces, and the excess pore water pressures in the backfill sand and geogrid strains. Comparing the results of the test models indicated that seismic waves with long-time high acceleration values from the far field had greater effects on the seismic behaviors of the reinforced retaining wall than those from the near field, and the geogrid could still effectively improve the seismic resistance deformation abilities of the saturated geogrid reinforced rigid retaining wall. Geogrid layers could decrease the development of excess pore water pressures and accelerate the dissipation of excess pore water pressures. The middle-layer geogrids in the reinforced soil played important roles in the seismic stability of the retaining wall, and the geogrid roots connected with the walls were key parts in the seismic design of the geogrid reinforced rigid retaining wall. Seismic waves from far or mid-far fields must be considered in the seismic designs of geogrid reinforced rigid retaining walls.