Grain Deformation of Fractured Sandstone and Stokes Local-rotation of Material Line

TL;DR

This study uses high-resolution XCT imaging to analyze mineral grain movement, rotation, and deformation in fractured sandstone under uniaxial compression, revealing distinct behaviors between fracture and non-fracture zones.

Contribution

It provides detailed microstructural insights into grain deformation and local rotation in sandstone, a novel application of XCT at this resolution for such analysis.

Findings

Shear strain is periodic radially.

Positive and negative shear strains show local concentration.

Different grain behaviors observed between fracture and non-fracture zones.

Abstract

The movement and deformation of mineral grains in rocks control the failure behavior of rocks. However, at high resolution, the physical and mechanical behavior of three-dimensional microstructures in rocks under uniaxial compression has not been characterized. Here, in suit XCT (4.6 um) has been applied to investigate the behavior of mineral grains of sandstone -- movement, rotation deformation and the principle strains obtained by deformation gradient tensor constructed with three principle axial vector representation of grain, indicating that the behavior of grains between the fracture and the non-fracture zone are different. For further investigate the behavior of grain cluster, the material lines are used to obtain the Stokes local rotation, namely shear strain. The finding is that: 1. the shear strain is periodic in the radial direction. 2. on average sense, the positive shear strain and negative shear strain have local concentration features.