[Purposes] The loading frequency not only affects the dynamic modulus of asphalt mixtures but also influences their fatigue life, to comprehensively reveal the impact of frequency on the structural mechanical behaviour of asphalt pavements, relevant research has been undertaken. [Methods] Establish finite element models under mobile loading conditions, develop iterative computational methods to determine response frequencies at varying depths, and conduct field strain measurements on tunnel asphalt pavements to validate models and algorithms. Employ iterative algorithms to compare and analyse the mechanical response and fatigue life of asphalt pavements with semi-rigid bases, flexible bases, and composite bases. [Findings] Compared with traditional algorithms (where all asphalt layers operate under 10Hz conditions), the iterative algorithm (at 70km/h traffic speeds) reduces maximum tensile stress at the base of composite and semi-rigid bases by 2.4% and 6.6% respectively, with virtually no impact on corresponding fatigue crack life. The maximum strain at the bottom of the lower layer beneath flexible base asphalt pavements decreased by 6.4%, while its fatigue life increased by 10%. When analysing heavy-load low-speed (60 km/h driving speed, double axle load) flexible base asphalt pavements using the iterative algorithm, the fatigue cracking life of the lower layer bottom exceeded that of the traditional algorithm by 30.9%. [Conclusions] Frequency variations not only affect the mechanical properties of asphalt pavements (due to modulus changes); the impact of superimposed frequencies on fatigue characteristics is significant, with notable alterations in the fatigue cracking life of flexible base asphalt pavements, warranting due attention.