Displacement mode has a significant influence on the distribution and magnitude of lateral earth pressures and the failure
mechanisms of retaining walls. This study performed five model tests to evaluate the responses of coarse sand-backfilled
retaining walls under five displacement modes including uniform translation (UT), rotation around the base (RB), rotation
around the top (RT), counter-clockwise rotation around the midpoint (RM-CC), and clockwise rotation around the midpoint (RM-C). The measured lateral earth pressures behind each wall were compared with the calculated values using the
analytical solutions from the literature. The failure mechanisms of the retaining walls under different displacement modes
were evaluated in terms of their backfill deformation and shear strain contours. Test results show that the measured
lateral earth pressures at rest and limit equilibrium (LE) had nonlinear distributions, and the RM-C mode resulted in the
largest LE earth pressures as compared with the other four modes. The comparisons show that the measured at-rest and LE
earth pressures were in good agreement with those calculated by Jaky’s method and Harrop-Williams’ method, respectively. For the retaining walls under the UT, RB, and RT modes, the required wall movement to reach the LE state was
approximately 0.4%H where H is the height of the retaining wall. For the retaining walls under the RM-CC and RM-C
modes, the required wall movements above the rotation point and below the rotation point to reach the limit equilibrium
were 0.4%H and 0.2%H, respectively. The backfill behind the wall under the RB or RM-C mode showed progressive
failure, while the backfill under the UT, RT, or RM-CC mode showed quick failure.