Experimental Study on the Dynamic Behavior of Marine Soft Soil Reinforced with Basalt Fibers

The dynamic performance of reinforced marine soft soil under cyclic loading is a critical concern in geotechnical engineering. This study presents a comprehensive investigation into the dynamic behavior of marine soft soil reinforced with basalt fibers through integrated dynamic triaxial testing, microstructural analysis, and theoretical modeling. The results demonstrate that fiber content and cyclic stress ratio (CSR) significantly influence the dynamic response. An optimal fiber content of 0.3% was identified to achieve maximum strength and minimal accumulated strain, while fiber content of 0.5% promoted the dissipation of dynamic pore water pressure. The reinforced soil exhibited enhanced resilience to cyclic loading, with dynamic strength increasing notably with CSR. Microstructural analysis revealed that basalt fibers interlock with soil particles, fill pores, and increase inter-particle friction, forming a denser and more stable soil matrix. Furthermore, a novel damage-modified hyperbolic model, incorporating Lemaitre’s damage theory, was developed to accurately characterize the nonlinear strain-cycle relationship and stiffness degradation under cyclic loading. The model demonstrated excellent fitting performance (R²>0.99). These findings provide valuable insights and a theoretical basis for the application of basalt fibers in improving the dynamic stability and seismic resilience of soft soil foundations.