VOLUMETRIC CHANGES IN ROCK SUBJECTED TO DIFFERENT STRESS PATHS

摘要:

The volumetric changes in Jinan gabbro and Changping granite subject ed to three different stress paths have been studied. In all cases the rockwas first loaded to a pre-determined stress state below that which would be conducive to fracture. This was then followed by three different cases of loading. Case A: The maximum principal stress was continuously increased to induce fracture. Case B: The minimum principal stress was decreased to induce fracture. Case C. The minimum principal stress was increased to prevent fracture. The experiments showed that for the same rock dilatant behaviour was different along different stress paths. When compared with the dilatant behaviour during case A experiments(i.e. the conventional triaxial experiments) the rocks were found to be in a superdense state for a case B stress path and in an ultra-dilatant state for a case C stress path.

Abstract:

The volumetric changes in Jinan gabbro and Changping granite subject ed to three different stress paths have been studied. In all cases the rockwas first loaded to a pre-determined stress state below that which would be conducive to fracture. This was then followed by three different cases of loading. Case A: The maximum principal stress was continuously increased to induce fracture. Case B: The minimum principal stress was decreased to induce fracture. Case C. The minimum principal stress was increased to prevent fracture. The experiments showed that for the same rock dilatant behaviour was different along different stress paths. When compared with the dilatant behaviour during case A experiments(i.e. the conventional triaxial experiments) the rocks were found to be in a superdense state for a case B stress path and in an ultra-dilatant state for a case C stress path.