Cyclic and Monotonic Behaviour of Coarse Mixed Soils from Debris Flow Slopes: Large-Scale Triaxial Insights

Loose, mixed-grain soils—common in debris flow-prone slopes like those in Upper Svaneti—are far more vulnerable to liquefaction and cyclic degradation than previously understood. Large-scale triaxial tests reveal that such soils can lose up to 90% of their stiffness and exhibit extreme damping (over 100%) when subjected to moderate cyclic stress ratios (CSR ≤ 0.4), particularly if they start with a void ratio ≥ 0.85. Denser soils, however, remain stable until CSR exceeds 1.0. The study also shows that load reversal patterns and initial stress conditions significantly accelerate pore pressure buildup, increasing the risk of slope failure. These findings provide critical data for hazard prediction in dynamic geological environments.

Mehrpajouh, A., & Engel, J. (2025). Cyclic and Monotonic Behaviour of Coarse Mixed Soils from Debris Flow Slopes: Large-Scale Triaxial Insights. Geotechnical and Geological Engineering, 43(9). https://doi.org/10.1007/s10706-025-03429-z