Deformation characteristics of high-porosity rock mass with a single flaw under axial loading and lateral restraint

Abstract

Rock-like replicas with different dip-angle flaws were tested in an apparatus with axial loading and lateral restraint to study the stress-strain characteristics of high-porosity rock with a single flaw. The results showed that a coefficient of the lateral stress could be calculated using a coefficient of the lateral frictional resistance and frictional coefficient. It was determined that the lateral stress increases linearly with axial loading. The relationship between the flaw aperture and loading can be described by an exponential function. The high-porosity rock mass with a single flaw exhibited a creep deformation, which was practically no creep deformation during an initial loading stage and then increased remarkably when the loading pressure exceeded the uniaxial compressive strength. The internal flaw affected a lateral deformation of the porous space for a high-porosity rock replica, which was limited to outside lateral deformation, and the porosity structure collapse was the main reason for the flaw closure. Elastic-plastic stage, collapse stage, and strain-hardening stage were investigated in the rock replica stress-strain process, and the strain-hardening process was generated after the flaw closure. The volumetric ratio of fracture volume to porosity was kept constant in the first loading process, and after the porosity structure collapsed, the ratio decreased quickly, and porosity deformation played a dominant role in the overall strain. This study provided a new understanding related to research of stress-strain characteristics of fractured-porous rock.