Deformation Characteristics and Failure Modes of Basalt Fiber Pisha Sandstone Cement‐Soil Under Multi‐Level Cyclic Loading

This study systematically investigates the influence of basalt fiber (BF) content on the deformation patterns and failure mechanisms of Pisha sandstone cement‐soil (PSC) composites under multi‐level cyclic loading (MLCL). Dynamic triaxial tests and X‐ray computed tomography (CT) analysis were employed to evaluate the performance of BF‐PSC specimens. The results indicate that the dynamic shear modulus (DSM) initially increases and then decreases with increasing BF content, while it gradually enhances with rising confining pressure. The damping ratio increases progressively with BF content but decreases with higher confining pressure. Under cyclic loading, failure initiates from both ends toward the center and from the periphery to the interior, with damage progression accelerating exponentially upon crack formation. Based on CT scan results, a mathematical model describing the dynamic failure pattern of BF‐PSC was established using fractal dimension theory, achieving a high fitting degree exceeding 0.98. The optimal BF content was identified as 0.3%, which increased the maximum DSM by up to 37.7% at 60 kPa confining pressure.