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Effect of Confining Pressure on the Dynamic Mode II Fracture Toughness of Rocks

  • Wei Yao
  • Tony Zhang
  • Kaiwen XiaEmail author
Conference paper
Part of the Conference Proceedings of the Society for Experimental Mechanics Series book series (CPSEMS)

Abstract

The dynamic shear failure of rocks with confinements is important in rock engineering and it is thus desirable to quantify the dynamic Mode II fracture toughness of rocks under confining conditions. This paper presents a punch-through shear (PTS) method to measure such material parameter of rocks under different confining pressures. A split Hopkinson pressure bar system with a Hoek cell is used to exert the dynamic PTS tests. The dynamic PTS specimen is a 50 mm diameter and 30 mm long cylinder with two 10 mm-deep circular notches at both ends. The finite element method is used to obtain equations calculating Mode II fracture toughness. The validity and applicability of the proposed method are demonstrated via the dynamic PTS tests of an isotropic and fine-grained Fangshan marble (FM) under five confining pressures. The PTS specimens are punched into a short rod and a hollow cylinder. The dynamic Mode II fracture pattern of the recovered FM are analyzed using the X-ray micro-CT technique. The results show that the rock specimen failure is shear dominant and the Mode II fracture toughness of FM increases with the loading rate under a certain confining pressure and increases with the lateral confinement at a given loading rate.

Keywords

Mode II fracture toughness Punch-through shear method SHPB Confinement FEM 

Notes

Acknowledgment

Funding was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) through the Discovery Grant No. 72031326.

References

  1. 1.
    Lukić, B., Forquin, P.: Experimental characterization of the punch through shear strength of an ultra-high performance concrete. Int. J. Impact Eng. 91, 34–45 (2016)CrossRefGoogle Scholar
  2. 2.
    Backers, T., Stephansson, O.: ISRM Suggested Method for the Determination of Mode II Fracture Toughness. In: Ulusay, R. (ed.) The ISRM Suggested Methods for Rock Characterization, Testing and Monitoring: 2007–2014 [S], pp. 45–56. Springer International, New York City (2015)Google Scholar
  3. 3.
    Yao, W., Xu, Y., Yu, C., Xia, K.: A dynamic punch-through shear method for determining dynamic Mode II fracture toughness of rocks. Eng. Fract. Mech. 176, 161–177 (2017)CrossRefGoogle Scholar
  4. 4.
    Zhou, Y.X., Xia, K., Li, X.B., Li, H.B., Ma, G.W., Zhao, J., Zhou, Z.L., Dai, F.: Suggested methods for determining the dynamic strength parameters and mode-I fracture toughness of rock materials. Int. J. Rock Mech. Min. Sci. 49, 105–112 (2012)CrossRefGoogle Scholar

Copyright information

© Society for Experimental Mechanics, Inc. 2020

Authors and Affiliations

  1. 1.Department of Civil and Mineral EngineeringUniversity of TorontoTorontoCanada

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