Abstract:The use of red clay, a widely-used material for subgrade-filling, easily results in the formation of an aggregate structure with different sizes, which means it has an important influence on the dynamic characteristics of soil. With the goal of investigating the effect of aggregate size on the dynamic characteristics of saturated red clay, a series of consolidation-undrained dynamic triaxial tests under different cyclic stress ratios were conducted in this study on compacted specimens prepared with different aggregate sizes (Dmax =5.0, 2.0 and 0.5 mm) using the dynamic triaxial apparatus GDS. The evolution of dynamic axial strain, dynamic elastic modulus, and damping ratio with aggregate size was analyzed. Several key findings are obtained. (1) The obvious increase in cumulative dynamic axial strain with increasing cyclic number is concentrated within the first 200 cycles, and such axial strain exhibits exponential growth as the cyclic stress ratio increases. (2) The more cumulative dynamic axial strain is observed from specimens prepared with larger aggregate sizes before the allowable cyclic stress ratio. In comparison, more cumulative dynamic axial strain is observed from specimens prepared with smaller aggregate sizes after the allowable cyclic stress ratio. (3) Under the same cyclic stress ratio, the dynamic elastic modulus and damping ratio of specimens with different aggregate sizes, almost align with the same growth tendency as the vibration times increased, thus indicating that the influence of aggregate size on dynamic elastic modulus and damping ratio is only obvious in the initial stage of cyclic loading.
