Numerical modelling of rock fracture

Key Researchers: Professor Anna Giacomini, Associate Professor George Kouretzis, Dr. Mason Crumpton.

PROBLEM DESCRIPTION

Fracture is an important failure mode which affects the cost, safety, and development speed of tunnels through rock, like those used in modern transport infrastructure and underground mining operations. Therefore, it is essential that engineers are equipped with tools for accurately modelling the initiation and propagation of cracks through rock while accounting for the complicated geometry, material behaviour, and loading conditions present in real-world tunnel designs. To achieve this, it is necessary to use computer-based simulation methods. However, programs available for solving geotechnical problems are largely based on techniques that are best suited for materials such as soil which remold under load and have limited capabilities for analysing problems involving brittle fracture. Moreover, specialised methods with fracture modelling capabilities typically rely on ad-hoc criteria for determining where crack initiation occurs and employ predefined or adaptively refined meshes that restrict potential propagation paths. To overcome these limitations, PRCGSE researchers at the University of Newcastle are developing efficient software based on novel phase-field finite element technologies for analysing the stresses, displacements, and fracture propagation paths around tunnels in rock.

SCIENTIFIC AND ENGINEERING APPROACHES

  • Implementation of realistic material models for capturing complex fracture modes in brittle rock caused by combined tensile, compressive, and shear stresses.
  • Development, implementation and calibration of staggered procedures to solve coupled equation
    systems for fracture paths and material displacements.
  • Validation of numerical modelling through comparisons with laboratory test results.
  • Simulation of large-scale underground openings to predict displacements, fracture paths and the onset of collapse.

APPLICATIONS

  • Calibration of material parameters for fracture analysis using laboratory tests on rock.
  • Prediction of stress states and displacements of tunnels under working conditions.
  • Identification of roof collapse mechanisms in underground mine roadways.
  • Calculation of displacements for developing Triger Action Response Plans (TARP’s)
  • Design of bolt and cable systems for supporting underground openings against collapse.