Study on the response characteristics and evolutionary mechanism of sandstone damage and fracture via real-time CT scanning and AE monitoring

Abstract Internal damage and degradation of rock structures under loading trigger deformation and fracture, leading to engineering disasters. To study the response characteristics, spatiotemporal correlations, and deformation/fracture mechanisms of rock physical quantities during loading stages, an independent real-time x-ray computed tomography (CT) scanning and acoustic emission (AE) monitoring platform was developed for uniaxial loading failure processes. Using digital volume correlation (DVC) and AE matrix inversion methods, the entire rock failure process was systematically characterized while deeply analyzing plastic-stage physical quantities to fully understand damage/fracture evolution mechanisms. Results reveal: (1) Fissure propagation, strain localization, and AE signal evolution exhibit similar spatiotemporal relationships during rock fracture; The response characteristics and response laws of each physical quantity showing sharp increases during the plastic stage provide precursor information for rock ultimate fracture instability. (2) Rock physical quantities in the plastic stage display spatiotemporal correlations - larger response coefficient <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>σ</mml:mi> <mml:mo accent="false">′</mml:mo> </mml:math> indicates stronger response capability and earlier precursor timing (sequence: AE signals &gt; deformation parameters &gt; fissure parameters); The nugget coefficient <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>C</mml:mi> <mml:mo accent="false">′</mml:mo> </mml:math> decreases abruptly to 88% during this stage, confirming significantly enhanced spatial correlation of physical quantities. (3) The conceptual model spanning rock strengthening-weakening-damage-failure-instability effectively verifies stress-driven progressive fracture mechanisms and spatiotemporal damage correlations.