EGU22-9482
https://doi.org/10.5194/egusphere-egu22-9482
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Local biaxial loading induced by end friction in uniaxial compression

Hongyu Wang1,2, Arcady Dyskin2, Elena Pasternak3, and Phil Dight1
Hongyu Wang et al.
  • 1Australian Centre for Geomechanics, Australia
  • 2Department of Civil, Environmental and Mining Engineering, School of Engineering, The University of Western Australia, Australia
  • 3Department of Mechanical Engineering, School of Engineering, The University of Western Australia, Australia

Rock samples tested in uniaxial compression tests are often observed to have spallation failure at the lateral surface of the sample caused by buckling of layers developing parallel to the direction of loading. These layers are caused by extensive crack growth. Yet, the experiments show that extensive crack growth in real 3D situations requires the presence of intermediate compressive principal stress (biaxial loading). We check the hypothesis that the intermediate principal stress is generated by the direct contact with metal loading platens, where the “frictional” boundary conditions are developed at the sample ends, creating non-uniform stress distributions near the sample ends. By the use of the finite element method (FEM), we analyse the stress distributions at the immediate lateral surface of the cylindrical sample in uniaxial compression in the polar coordinate system. It is found that near the ends the sample is actually biaxially loaded: the circumferential stress could be induced to play the role of the intermediate principal stress. The sizes of the zones and the maximum magnitude of the circumferential stress depend upon the friction coefficient and the Poisson’s ratio of the rock. The biaxial load ratio is defined by the ratio between the circumferential compressive stress and the axial stress. Comparing the biaxial load ratio determined in numerical models with the critical biaxial load ratio inducing extensive crack growth, the spallation of rock samples in uniaxial compression tests can be interpreted from a new perspective.

How to cite: Wang, H., Dyskin, A., Pasternak, E., and Dight, P.: Local biaxial loading induced by end friction in uniaxial compression, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9482, https://doi.org/10.5194/egusphere-egu22-9482, 2022.