Dynamic Stiffness and Damping of Rigid Retaining Wall under Seismic Loading

Dynamic stiffness and damping of the soil under the base of the foundation of the retaining wall and the backfill soil behind it play the main role in estimating vibrating displacement during seismic loading. The purpose of the present study is to investigate the effect of dimensionless frequency (ao) on the horizontal, vertical, and rocking dynamic stiffness and dynamic damping of rigid retaining walls. On the other hand, the effect of (ao) and height of the retaining wall on the stiffness and damping for backfill soil behind the rigid retaining wall was also investigated in the cases of active and passive dynamic sliding and dynamic rocking. The study demonstrated that the dynamic stiffness and damping of the soil under the base of the rigid retaining wall increased with the soil shear modulus. While the dynamic stiffness and damping of the backfill soil behind the retaining wall increased with the wall height. The percentage of increment generally varied between (42.1 – 113.2)% when the height of the retaining wall rose from (4 to 6) m. The maximum horizontal, rocking, and vertical dynamic stiffness of the soil under the base of the foundation of the retaining wall occurred at high, low, and intermediate values of (ao), respectively, i.e., at high, low, and intermediate values of angular frequencies (ω) for constant values of soil properties and retaining wall height. It can be also noted that the values of dynamic sliding damping and dynamic rocking damping of the backfill soil decreased and increased with increasing the (ao) or (ω), respectively. The percentages of decrement and increment were (37.5)% and (183.3)% when (ao) increased from (0.19 to 1.35), respectively.