Consolidation Creep Behavior and Settlement Prediction of Fibrous Organic Soils in Seasonally Frozen Regions

Abstract

Fibrous organic soils are widespread and associated with long-term settlement of transportation infrastructure owing to their low bearing capacity, high compressibility, and pronounced creep, particularly in seasonally frozen regions. Undisturbed samples with fiber contents of 21%, 34%, 48%, 59%, and 73% from Northeast China underwent one-dimensional consolidation creep tests under consolidation pressures of 12.5–400 kPa. Results showed that higher-fiber-content groups exhibited larger axial strains under the same pressure. At 400 kPa, the final axial strain increased from 48.35% for the 21% fiber-content group to 61.98% for the 73% group. The coefficient of consolidation decreased rapidly as pressure increased and stabilized at 100–200 kPa, consistent with progressive compression and restricted drainage. The secondary compression index ranged from 0.022 to 0.064, generally increased with fiber content, and peaked at 50–100 kPa. Based on the ternary viscoelastic rheological (TVR) model, a finite-deformation TVR (FD-TVR) model was developed by introducing logarithmic strain and evolving drainage geometry while retaining the spring-Kelvin structure. Relationships between the model parameters, fiber content, and consolidation pressure were established, and FD-TVR predictions showed good agreement with the measured settlement curves. These findings may support settlement assessment and durable subgrade design, with implications for reduced maintenance and resource use.