A creep constitutive model incorporating deformation mechanisms for crushable calcareous sand

摘要

Due to the high compressibility and low crushing strength induced by remarkable intra-granular void and highly irregular shape, the creep response of calcareous sand is far larger than that of silica sand. Unlike silica sand, the creep behavior of calcareous sand under general stress might be divided into the initial near-linear phase, damping phase, and the steady phase. The three-phase creep behavior is difficult to be well described by general creep models, such as Burgers viscoelastic model. This paper conducted two sets of triaxial creep tests of calcareous sand under general stress state, finding that the three-phase creep is mainly governed by the mechanisms of grain rearrangement, interparticle friction, and particle crushing, respectively. Local instability near cavities on calcareous particles leads to specific initial near-linear phase and damping phase compared to silica sand. Further, a new creep constitutive model was established using different theological components to theoretically describe the creep characteristics of calcareous sand. The constitutive model was validated and proved to describe creep behavior of calcareous sand reasonably with the test data.