Influence of anisotropy on structural dynamic response, from the views of mechanism, analysis method, and implications for pavement design

While anisotropic properties of road materials have been extensively investigated, their systematic integration into pavement design frameworks remains incomplete. This study systematically reviews the mechanisms, characteristics and structural implications of material anisotropy in pavement systems through a layered analysis approach (asphalt surface, base and subgrade). The work evaluates three critical dimensions: experimental metrics and characterisation methods for anisotropy quantification, analytical techniques integrating anisotropic behaviour in structural design and anisotropy-induced performance degradation mechanisms. Key findings reveal that compressive modulus predominates as the primary anisotropy indicator in existing studies. Structural consequences include asphalt layer anisotropy exacerbating rutting severity and fatigue deterioration, base layer anisotropy diminishes pavement stress resistance and subgrade anisotropy amplifying permanent deformation. The paper concludes with the following research priorities: mechanistic modelling of anisotropy genesis and its evaluation protocols, field testing innovations for anisotropy assessment and inverse analysis methodologies for parameter identification. This synthesis establishes a foundational framework for advancing anisotropy-aware pavement engineering practices.