Hysteresis observed in stress-strain diagrams and its relation to adhesion hysteresis and stick-slip sliding in sedimentary granular rocks

Stress-strain behavior of sedimentary granular rocks are quite different from that of materials such as metals in that they exhibit large hysteresis. We have conducted uniaxial stress cycling measurements on various dry sandstone samples to observe in more detail the hysteresis in stress-strain diagrams and to understand the strain amplitude dependence of elastic moduli and attenuation. We have also tested fully saturated Berea sandstone samples using brine and CTAB (a cationic surfactant) as saturants. CTAB was chosen in order to investigate the relative contributions of adhesion hysteresis and stick-slip sliding on attenuation in sedimentary granular rocks. Young’s moduli and Poisson’s ratios obtained from the cycling tests show a significant dependence on strain amplitude at low and moderate overburden stresses. The type of fluid in the pore space and at the grain contacts has a large influence on the hysteresis observed in the stress-strain diagrams.