Effects of Pore Structures on Static Mechanical Properties of Sandstone

This paper presents a numerical and experimental investigation on the effects of pore structures on the static mechanical properties of porous sandstone. Three-dimensional (3D) numerical models of porous sandstone with different statistical pore parameters are constructed using a software program and the experimentally acquired data of the parameters. The mechanical properties of sandstone are numerically tested using Brazilian disc split tests to probe the influences of pore structures. A number of physical models having similar statistical characteristics of pores and physical properties with those of the numerical models are produced using modeling materials. Brazilian disc tests and computer tomography tests are performed on the physical specimens with different porosities to clarify the responses of pore structures during failure processes. The numerical analysis implies that pores significantly affect the mechanical properties of porous sandstone such as stress concentration, distribution, and the connection of the failed material elements. It is shown that the statistical distribution of pore radii presents a certain degree of influence on the split failure behavior of porous rock, which is closely related to rock porosity. However, distribution of spatial location of pores has negligible influence on stress distribution, failure mechanisms, and the split tensile strength of the porous media. A porosity of 15% seems to be a threshold porosity, above which the effects of geometrical and statistical characteristics of pore structures on the split mechanical properties of porous rock become significant. The laboratory test verifies that the developed physical models have consistent geometric and statistical characteristics of pores with those of the real sandstone. The measured split mechanical properties of the physical models present good agreement with the predictions of numerical simulations. (C) 2013 American Society of Civil Engineers.