Dynamic Response of Unsaturated Silty Soil from Small to Large Strains Using Resonant Column and Torsional Shear Tests
摘要
This study presents an experimental investigation into the dynamic behavior of a low-plasticity silty soil under varying matric suction and net confining stress conditions. A custom-built, suction-controlled resonant column torsional shear (RCTS) device was used to evaluate the shear modulus and damping ratio over a wide range of shear strains. Tests were conducted on specimens subjected to matric suctions ranging 0 and 200 kPa and net confining pressures of 50 and 100 kPa. The results show that the small-strain shear modulus (Gmax) increases with matric suction due to enhanced capillary bonding and suction-induced stiffness. Conversely, the damping ratio decreases with increasing suction, reflecting reduced energy dissipation during cyclic loading. At larger strain levels, both shear modulus and damping ratio become less sensitive to suction, indicating a transition from suction-dominated to friction-dominated behavior. The variation of normalized shear modulus and damping ratio with shear strain was analyzed and compared with existing empirical models. While the trends generally agree at small strains, notable deviations were observed at higher strain levels, particularly under greater confinement. These discrepancies highlight the limitations of traditional models developed for saturated soils when applied to unsaturated conditions.