Using fiber, lime and fly ash to modify iron tailings and apply them to a road base is an effective way to utilize iron tailings as resources. To explore the influence of fiber on lime and fly ash-stabilized iron tailings (EIT) under dry and wet cycles at an early curing age, the static and dynamic characteristics of EIT and fiber-modified lime and fly ash-stabilized iron tailings (FEIT) under dry and wet cycles were studied through an unconfined compressive strength (UCS) test, splitting test and dynamic triaxial test. The results show the following. (1) EIT and FEIT still have high UCS and splitting strength after dry–wet cycles, and the dry–wet cycles can promote the static properties of FEIT. (2) The dry–wet cycle is the main factor affecting the change in the dynamic elastic modulus of EIT and FEIT. The dynamic elastic modulus of EIT first increases and then decreases with the increase in dry–wet cycles, and the dynamic elastic modulus of FEIT first decreases and then increases with the increase in dry–wet cycles. The damping ratio of EIT and FEIT decreases with the increase in dry–wet cycles, and then tends to be stable. (3) After seven dry–wet cycles, the compressive performance, tensile performance, deformation resistance and vibration resistance of FEIT are better than those of EIT. This study can provide a reference for the resource application of iron tailings in road engineering.

In recent years, expanded polystyrene (EPS) lightweight soil has been widely used as subgrade in soft soil areas because of its light weight and environmental protection. This study aimed to investigate the dynamic characteristics of sodium silicate modified lime and fly ash treated EPS lightweight soil (SLS) under cyclic loading. The effects of EPS particles on the dynamic elastic modulus (Ed) and damping ratio (λ) of SLS were determined through dynamic triaxial tests at various confining pressures (σ3), amplitudes, and cycle times. Mathematical models of the Ed of the SLS, cycle times, and σ3 were established. The results revealed that the EPS particle content played a decisive role in the Ed and λ of the SLS. The Ed of the SLS decreased with an increase in the EPS particle content (EC). The Ed decreased by 60% in the 1–1.5% range of the EC. The existing forms of lime fly ash soil and EPS particles in the SLS changed from parallel to series. With an increase in σ3 and amplitude, the Ed of the SLS gradually decreased, the λ generally decreased, and the λ variation range was within 0.5%. With an increase in the number of cycles, the Ed of the SLS decreased. The Ed value and the number of cycles satisfied the power function relationship. Additionally, it can be found from the test results that 0.5% to 1% was the best EPS content for SLS in this work. In addition, the dynamic elastic modulus prediction model established in this study can better describe the varying trend of the dynamic elastic modulus of SLS under different σ3 values and load cycles, thereby providing a theoretical reference for the application of SLS in practical road engineering.