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A Theoretical and Experimental Study of Stress���Strain, Creep and Failure Mechanisms of Intact Coal

Journal Article


Abstract


  • Deep mining and drilling activities typically trigger significant deformation of coal/rock roadway and even coal/rock dynamic hazards, which has attracted considerable attention. Hence, in this article, the mechanics and failure properties of intact coal are examined through triaxial compression tests and creep tests. First of all, triaxial compression experiments demonstrated that the complete stress���strain curves of intact coal are characterised by Class-I behaviour; and the post-peak modulus is negative. Second, with increasing confining pressure, peak strength and residual strength rise linearly, whereas elasticity modulus and peak strain increase as a power function form. Thirdly, compared with conventional triaxial load, tiered cyclic load can stiffen the strength of intact coal. Moreover, the data of creep tests are successfully fitted to the Burgers model. Maxwell elasticity modulus is significantly smaller than other creep parameters; Maxwell viscosity coefficient shows a positive correlation with deviatoric stress. Contrarily, Kelvin elasticity modulus and Kelvin viscosity coefficient drop with the rise in deviatoric stress. Additionally, with increasing deviatoric stress, single-step creep strain and average creep strain rate, proposed in this study, increase in a power function form. Finally, failure characteristics of intact coal under triaxial stress could be classified into four types (mainly shear failure and multiple shear fractures). The failure-plane angle generally linearly increases with the rise in confining pressure applied.

Publication Date


  • 2020

Citation


  • Zhang, L., Li, X., & Ren, T. (2020). A Theoretical and Experimental Study of Stress���Strain, Creep and Failure Mechanisms of Intact Coal. Rock Mechanics and Rock Engineering, 53(12), 5641-5658. doi:10.1007/s00603-020-02235-8

Scopus Eid


  • 2-s2.0-85090058705

Start Page


  • 5641

End Page


  • 5658

Volume


  • 53

Issue


  • 12

Place Of Publication


Abstract


  • Deep mining and drilling activities typically trigger significant deformation of coal/rock roadway and even coal/rock dynamic hazards, which has attracted considerable attention. Hence, in this article, the mechanics and failure properties of intact coal are examined through triaxial compression tests and creep tests. First of all, triaxial compression experiments demonstrated that the complete stress���strain curves of intact coal are characterised by Class-I behaviour; and the post-peak modulus is negative. Second, with increasing confining pressure, peak strength and residual strength rise linearly, whereas elasticity modulus and peak strain increase as a power function form. Thirdly, compared with conventional triaxial load, tiered cyclic load can stiffen the strength of intact coal. Moreover, the data of creep tests are successfully fitted to the Burgers model. Maxwell elasticity modulus is significantly smaller than other creep parameters; Maxwell viscosity coefficient shows a positive correlation with deviatoric stress. Contrarily, Kelvin elasticity modulus and Kelvin viscosity coefficient drop with the rise in deviatoric stress. Additionally, with increasing deviatoric stress, single-step creep strain and average creep strain rate, proposed in this study, increase in a power function form. Finally, failure characteristics of intact coal under triaxial stress could be classified into four types (mainly shear failure and multiple shear fractures). The failure-plane angle generally linearly increases with the rise in confining pressure applied.

Publication Date


  • 2020

Citation


  • Zhang, L., Li, X., & Ren, T. (2020). A Theoretical and Experimental Study of Stress���Strain, Creep and Failure Mechanisms of Intact Coal. Rock Mechanics and Rock Engineering, 53(12), 5641-5658. doi:10.1007/s00603-020-02235-8

Scopus Eid


  • 2-s2.0-85090058705

Start Page


  • 5641

End Page


  • 5658

Volume


  • 53

Issue


  • 12

Place Of Publication