Strain, pore pressure and fatigue characteristics of sandstone under various load conditions

Abstract

This paper presents results of an experimental study of the strain, pore water pressure and fatigue characteristics of a saturated sandstone under quasi-static, repeated and cyxlic loadings. Based on the experimental results, a relation between the accumulation of axial strain and the fatigue life of the sandstone studied was established. It was found that under some testing conditions there exists a critical axial strain beyond which the failure of the specimens will occur almost immediately. Variation of the pore water pressure in the sandstone under various loadings was observed and interpreted. Three distinct modes of pore water pressure variation were observed in the cyclic loading process. For all loading conditions studied, the pore water pressure induced in the rock specimens drops rapidly right before the failure. The variation of the pore water pressure was interpreted in terms of internal structural changes of the rock specimens.