Mechanical behaviour of an artificially microcracked marble

To investigate the influence of microcracking conditions on the mechanical bahaviour of rocks, a homogeneous isotropic rock (Carrara marble) was slowly heated at temperatures from 50 to 300"C. On these specimens, tests were carried out to determine strength, deformability and dynamic properties in uniaxial and triaxial conditions. Static deformability and dynamic properties are markedly reduced by even only mild microcracking, whereas strength is less influenced. The effect of microcracking is felt more in tensile conditions and less in uniaxial compression conditions. The influence of saturation and of the applied load on the compressional and shear wave velocities is also discussed and the results are compared with some theoretical models of microcracked media.