Polypropylene fiber and cement were used to modify iron tailings and applying it to roadbed engineering is an important way to promote the sustainable development of the mining industry. However, the existing studies are mostly concerned with the static mechanical properties, and lack the deformation characteristics of cyclic loading under different loading modes. The effects of fiber content, dynamic-static ratio (Rcr) and curing age on the deformation characteristics of fiber cement modified iron tailing (FCIT) under different cyclic loading modes were explored through dynamic triaxial tests. The research results show that: (1) Polypropylene fibers significantly reduced the cumulative strain of FCIT. Under intermittent loading, the cumulative strain decreased by 36 similar to 43 %, and under continuous loading, the cumulative strain decreased by 48 similar to 55 %. (2) The deformation behavior of FCIT under both intermittent and progressive loading was in a plastic steady state with cumulative strain <= 1 %. (3) The cumulative strain variation of FCIT with intermittent loading of 0.316 % was significantly lower than that with continuous loading of 0.417 %, and the resilience modulus was higher with intermittent loading. (4) The stress history effect of step-by-step loading can be eliminated by the translational superposition method, and the strain evolution law under continuous loading is predicted based on the progressive loading data, and the minimum error between the expected and actual results is 6.5 % when Rcr is 0.1.

Considering the engineering background of the dangerous western mountain railroad, large-scale shaking table model experiments were conducted on embankment slopes supported by single and double-row piles, subjected to El-Centro wave excitations. Based on parameters such as displacement and acceleration, an in-depth investigation was conducted to study the differences in dynamic response characteristics between the two slope models. Moreover, the reasons for the differences between the two slopes were explored using fast Fourier transform (FFT) spectra. The results revealed that both the support effect and the differences in anti-slip piles gradually increased with the increase in the input wave amplitude. At input wave amplitudes of 0.1g-0.3g, both single and double-row pile slopes remained stable, with minimal differences in their overall dynamic response characteristics. However, at an input wave amplitude of 0.4g, significant differences in the dynamic responses of both slopes emerged. Macroscopic damage was more apparent in the single-row pile slope, with high slope surface displacement, accumulated soil damage, and noticeable nonlinear characteristics. At an input wave amplitude of 0.5g-0.6g, both slope models exhibited a pronounced elevation effect in the peak ground acceleration (PGA) amplification factor. Additionally, plastic zones were observed on the road cut face and behind the piles in both models. The presence of retaining piles effectively suppressed the upward trend of PGA amplification coefficients along the slope and prevented the connection of plastic zones on the slope surface. Notably, the PGA amplification effect of the single-row pile slope was pronounced, with a wide and deep plastic zone, severe local instability, and relatively weak seismic support effect. The introduction of the FFT spectral ratio revealed that the difference in amplitude amplification effects of single and double-row pile slopes in the 5-10 Hz band was the main reason for the difference in their dynamic responses. Under seismic loading, the failure process of the single-row pile-supported slope involved three stages: initial stability of the slope, plastic deformation of the slope surface soil, and local collapse and disintegration of the slope. In contrast, the double-row pile-supported slope experienced the first two stages of this failure process.