jats:p Dual-row retaining walls can be utilised to form embankment structures for protection against tsunamis or as port structures. The dynamic response of these walls involves a complex interaction between the soil and structural elements which is not well understood. In this paper, for the first time a combination of centrifuge and finite-element modelling is used to better understand the mechanical response of the combined wall–soil system. The measured variation of the horizontal stresses leads to bending moment distributions featuring large, singly outward bending or double curvature with significant inward bending of the wall near the ground level. The numerical analyses are used to understand the stress state and highlight the dynamic variations of the vertical effective stress that drive this previously unexplained behaviour. The shear stresses that can develop at the wall–soil interface govern the mechanism by which the vertical effective stresses can vary. Further consideration of the dynamic soil stress state suggests a purer interpretation of the limiting loads in soil–structure interaction problems relative to the traditionally defined dynamic earth pressure coefficients. Combining the altered vertical soil stresses with earth pressure coefficients depending only on the soil friction angle adequately bounds the horizontal stresses that develop in the soil. </jats:p>