Presentation Information
[2401]Mechanical Behaviour and Fracture Response of Geomaterials under Confinement and Impact
○Qianbing Zhang1 (1. Monash University)
Chairperson:
Keywords:
Mining Geomaterials,Static-Dynamic Loading,Tri-HB,Continuum-Discrete Coupled Modelling
Deep mining excavations are increasingly subjected to high in-situ stresses, blasting disturbances, mining-induced seismicity, and rockburst hazards. Under these conditions, geomaterials and support systems experience transient dynamic impacts while confined by static stresses, resulting in rapid crack initiation, fracture coalescence, strength degradation, and sudden instability. However, the mechanisms linking confined impact loading, fracture evolution, and meso-scale damage remain insufficiently understood. This study presents an integrated experimental and numerical framework to investigate the mechanical behaviour and fracture response of geomaterials under coupled static-dynamic loading. The experimental programme employs a Triaxial Hopkinson Bar system capable of applying impact loading to 50 mm cubic specimens under controlled biaxial or triaxial confinement. The system can generate impact velocities of up to 50 m/s and confining stresses of up to 100 MPa, enabling the simulation of deep underground stress conditions. A continuum-discrete coupled modelling approach is adopted to interpret the experimental observations. The continuum domain represents loading bars, confinement boundaries, and stress-wave propagation, while the discrete element domain captures particle bonding, bond breakage, crack initiation and propagation, force-chain evolution, and fragment formation. Geomaterials with inherent discontinuities and concrete-based support materials are selected as representative materials. For heterogeneous geomaterials, structural features such as bedding planes, joints, cleats, and weak layers govern crack propagation, displacement localisation, and stress redistribution under impact loading. In concrete-based support materials, aggregates, matrix, interfaces, and fibres control matrix cracking, interface debonding, crack deflection, fibre bridging, and energy dissipation, resulting in a more distributed fracture network. By linking macroscopic dynamic response with internal fracture characteristics and meso-scale damage mechanisms, the proposed framework provides new insights into dynamic instability, blasting-induced damage, rockburst failure, and the degradation of underground support systems in deep mining environments.