An Experimental Investigation into the Influence of Environmental and Fabric Parameters on the Behaviour of Sandstones

Abstract

<p>An experimental study has been carried out to determine the effects of environmental and fabric parameters on the deformational behaviour of sandstones. Confining pressures ranged from 1-2500 bars, total strains 0.5-20.0 percent, and strain rates 10^-5 - 10^-7 per second.</p> <p>The modes of deformation are found to be strongly dependent on confining pressure, total strain, and composition. All rocks tested show the customary increase in strength with increasing confining pressure. The ultimate strength is found to be inversely proportional to the mean grain size of the framework, and calcite content. Unconfined compressive strengths and elastic properties are strongly dependent on porosity. Ductility is enhanced by increasing calcite content and increasing confining pressure, but is not influenced by clast variation in the framework.</p> <p>The deformational mechanisms are shown to be functions of the rock's fabric and confining pressure. Extensional microfracturing in the quartz grains of a calcareous sandstone and an arenaceous carbonate are controlled by the Poisson's ratio of quartz and calcite, and the volume fraction of the quartz grains.</p>