Complexities in mechanical behaviours of rock masses mainly stem from inherent discontinuities, which calls for advanced bolt-grouting techniques for stability enhancement. Understanding the mechanical properties of bolt-grouted fractured rock mass(BGFR) and developing accurate prediction methods are crucial to optimize the BGFR support strategies. This paper establishes a new elastoplastic(E-P) model based on the orthotropic and the Mohr-Coulomb(M-C) plastic-yielding criteria. The elastic parameters of the model were derived through a meso-mechanical analysis of composite materials mechanics(CMM). Laboratory BGFR specimens were prepared and uniaxial compression test and variable-angle shear test considering different bolt arrangements were carried out to obtain the mechanical parameters of the specimens. Results showed that the anisotropy of BGFR mainly depends on the relative volume content of each component material in a certain direction. Moreover, the mechanical parameters deduced from the theory of composite materials which consider the short fibre effect are shown to be in good agreement with those determined by laboratory experiments, and the variation rules maintained good consistency. Last, a case study of a real tunnel project is provided to highlight the effectiveness, validity and robustness of the developed E-P model in prediction of stresses and deformations.

fundedbytheNationalKeyResearchandDevelopmentPlan(No.2022YFC3203200)；DepartmentofScienceandTechnologyofGuangdongProvince(No.2021ZT09G087)；theNationalNaturalScienceofChina(No.42167025)；

1.Introduction
2.Elastic model for BGFR
2.1.Orthotropic elastic model of BGFR
2.2.Determination of elastic parameters
2.2.1.Determination of E1
(a) The calculation of E1x
(b) The calculation of E1y
2.2.2.Determination of E2
(a) The calculation of E2x
(b) The calculation of E2y
2.2.3.Determination of E3
(a) The calculation of E3x
(b) The calculation of E3z
2.2.4.Determination of v12/v21,v13/v31,and v23/v32
2.2.5.Determination of G12,G23,and G13
3.Plastic constitutive model of BGFR
3.1.Plastic model of BGFR
3.2.Plastic yielding criterion
3.2.1.Matrix failure
3.2.1.1.Shear failure.
3.2.1.2.Tensile crack.
3.2.2.Bolt failure
3.2.2.1.Tensile yielding of bolt.
3.2.2.2.Shear yielding of grout annulus.
3.2.3.Fracture failure
3.2.3.1.Fracture sliding.
3.2.3.2.Fracture tensile cracking.
4.Laboratory testing methodology
4.1.Preparation of sample
4.2.Experimental scheme and procedure
4.3.Results of UCT
4.4.Results of VST
5.Discussion
6.Case study
7.Conclusions

[1]Li H ,Zuo S ,Lin P .A new elastoplastic model for bolt-grouted fractured rock[J].International Journal of Mining Science and Technology,2024,34(07):995-1016.