The investigation of seepage model for columnar jointed rock masses during cyclic loading and unloading of confining pressure

Abstract

Columnar jointed rock masses (CJRM) as a type of jointed rock masses with the distinct structure are widely distributed in nature and have received considerable attention during the last few decades. In this paper, an approach, which is a combination of experiment and graphing method, is proposed to verify the existence of a representative elementary volume (REV) of CJRM during cyclic loading and unloading of confining pressure based on physical model permeability experiments. According to the experiment results, mathematical models for calculating permeability tensor of CJRM were established, and the major principal permeability component (PPC), the minor PPC, and the principal permeability angle (PPA) of CJRM during cyclic loading and unloading of confining pressure are calculated. It was concluded that the existence of a REV of CJRM during cyclic loading and unloading of confining pressure can be verified easily by using the proposed method. During cyclic loading and unloading of confining pressure, a REV does not always exist, especially at high confining pressure. The impacts of confining pressure on the major PPC, the minor PPC, and the PPA are large in the first cyclic loading phase.