The effect of loading frequency on the long-term cyclic behavior of dense calcareous sand

Transportation infrastructure foundations filled with calcareous sand are exposed to long-term cyclic loading under various frequencies. This study presents experimental results about the drained cyclic triaxial tests conducted on dense calcareous sand under different mean effective stresses (p00), cyclic stress ratios ('), and loading frequencies (f) to examine the effect of f on the long-term cyclic behavior. Results show that the increase in f causes the significant increase in the accumulated axial strain (8qacc). As '' increases, 8qacc becomes more sensitive to f, while the increase of p0 could limit the aggravating effect of f on 8qacc. At a higher '', increasing f can even lead to a failure and larger dilated volumetric strain of dense calcareous sand specimens. The increase in f has a considerable impairing effect on the shakedown behavior, which can cause the stable shakedown behavior to transform into transitional or unstable shakedown behaviors. More accurate shakedown discriminant boundaries suitable for calcareous sand under different f were therefore proposed.