Experimental study on the evolution of rock microstructure under dynamic water pressure

Abstract

The pore structure of rocks has an important influence on their mechanical strength and permeability. In this experiment, the evolution of the internal multiscale structure of rocks under the action of seepage flow is investigated. The results show that progressive damage occurs inside the rock at the early stage of osmotic pressure action, and the expansion and connectivity of pores form a damage mutation at a certain moment, which triggers rock damage destabilization. In addition, a damage evolution equation based on NMR test values is established to obtain the threshold of damage mutation in rocks; It is also found that rock permeability is mainly affected by pore connectivity, and the effect of porosity on rock permeability is relatively small.