Study on Mechanical Properties and Damage Characteristics of Fiber-Reinforced Ecological-Matrix-Cemented Aeolian Sand Materials

To improve the quality of trench, backfill projects, this study utilizes solid waste to prepare a controllable low-strength material. Through uniaxial compression, three-point bending tests, and scanning electron microscopy (SEM), the mechanical performance evolution and fiber reinforcement mechanisms of the backfill material are revealed. Based on a two-parameter Weibull distribution probability model, an intrinsic correlation between the number of freeze–thaw cycles, damage variables, and compressive strength is established. The research results indicate that when the NaOH content is 3%, the water-to-solid ratio is 0.4, and the number of freeze–thaw cycles is 0, the sample’s mechanical properties reach their local optimum. After curing for 28 days, a significant amount of amorphous gel-like substance is formed inside the system, filling the intergranular spaces between aeolian sand particles, resulting in a relatively dense structure for the backfill material. In response to the degradation caused by the initial defects in the sample, fibers effectively prevent crack initiation. Based on the stochastic characteristics of freeze–thaw damage, the number of freeze–thaw cycles (n) follows the Weibull distribution model well. Using experimental data, evolution equations for the number of freeze–thaw cycles, intrinsic damage, and compressive strength were developed, ultimately establishing the intrinsic relationship between sample damage and strength. The findings provide theoretical support for addressing trench backfill engineering disasters in seasonally frozen regions.

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