Drained triaxial tests on mechanical properties of calcareous sand under various stress paths

The mechanical properties of calcareous sand are low in strength and easy to crush and have the characteristics of stress path dependence. In order to study the effects of different stress paths on the particle crushing and mechanical properties of calcareous sand, a series of drained triaxial compression tests under five stress paths are carried out on calcareous sand with different consolidation pressures. The results show that the stress path has a great influence on the stress-strain relationship, shear strength and particle breakage of the calcareous sand. Under the same consolidation pressure, the dilation phenomenon is obvious in the constant axial stress tests where the particle breakage index is the smallest, and the peak internal friction angle is the largest. The dilation phenomenon is less noticeable in the constant confining pressure tests with the largest particle breakage index and the smallest peak internal friction angle. These properties of the constant average principal stress tests are in between the above tests. The isotropic principal stress ratio tests and the isotropic stress consolidation tests mainly show the volume compression of samples during loading, so they are very different from the other three stress path tests. The influence factors of different stress paths on the stress-strain relationship and strength of calcareous sands, in addition to the characteristics of sands with stress path dependence, mainly come from the effects of inconsistent particle breakage caused by different stress paths and consolidation pressures. This is why the mechanical properties of the calcareous sand show great differences in the tests with different stress paths.