Section 2.3 - Elasticity of Porous Materials

Abstract

The methods used to determine the elasticity of porous materials and/or particulate materials as geomaterials or powderlike materials are distinct from those used with metals. The reason is that such materials possess pores and/or microcracks. For various stress states these may either open or close, thus influencing the values of the elastic parameters. Also, the stress-strain curves for such materials are strongly loading-rate-dependent, starting from the smallest applied stresses, and creep is exhibited from the smallest applied stresses. Thus information concerning the magnitude of the elastic parameters cannot be obtained from the initial slope of the stress-strain curves, since these are loading-rate-dependent. The elastic parameters can be determined experimentally by two procedures: dynamic and static procedures. With the dynamic procedure, one can determine the travel time of the two elastic (seismic) extended body/longitudinal and transverse waves, which are traveling in the body. The static procedure takes into account that the constitutive equations for geomaterials are strongly time-dependent.