Static and dynamic undrained shear behaviour of calcareous sand

The purpose of the present study is to investigate and clarify the undrained behaviour of Calcareous sand under monotonic and cyclic loading. Undrained monotonic and cyclic triaxial tests were performed with various magnitudes of initial static shear stress. The test results of calcareous sand were compared with those of Toyoura sand. At first, as a result of monotonic triaxial tests, it was found that the strength in compression side of Calcareous sand is larger than that of Toyoura sand, while in the extention side, it was smaller. Then, after performing cyclic triaxial tests, it was shown that the relationship between cyclic shear stress ratio and number of cycles to develope a large amplitude of axial strain in Calcareous sand is almost as same as Dr=70% of Toyoura sand. Further, it was found that the dynamic strength increased with the initial static shear stress. Finally, it was recognized that there is a unique correlation between peak axial strain and peak effective stress ratio that can be evaluated by a hyperbola.