Authors: P Baud S Vinciguerra C David A Cavallo E Walker T Reuschlé
Publish Date: 2009/05/20
Volume: 166, Issue: 5-7, Pages: 869-898
Abstract
We investigated systematically the micromechanics of compaction in two carbonates of porosity above 30 Majella grainstone and Saint Maximin limestone The composition grain size and pore surface area of these rocks were determined Hydrostatic compression experiments were performed under dry and wet conditions beyond the onset of grain crushing A significant water weakening effect was observed in both rocks A set of conventional triaxial experiments was also performed on both rocks under dry conditions at confining pressures ranging from 3 to 31 MPa Microstructural observations were carried out on the deformed samples The mechanical behavior of these high porosity carbonates is dominated by shearenhanced compaction associated in most cases with strain hardening Stressinduced cracking and grain crushing are the dominant micromechanisms of deformation in both rocks In Majella grainstone compactive shear bands appeared at low confinement in qualitative agreement with the deformation bands observed in the field At higher confining pressures compaction localization was inhibited and homogeneous cataclastic flow developed In Saint Maximin limestone compaction localization was observed at all confining pressures An increasing number of compactive shear bands at various orientations appeared with increasing strain These new data suggest that compaction localization is important in the mechanical compaction of high porosity carbonates
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