A theoretical method of mechanical analysis for a circular tunnel reinforced by fully grouted rock bolts

Liu, Yijie; Lu, Aizhong; Zeng, Xiangtai

doi:10.1177/10812865211053371

Cited by 5 publications

(2 citation statements)

References 18 publications

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“…As mentioned above, the effect of point-anchored rock bolts on the surrounding rock can be regarded as pairs of concentrated forces of equal magnitude acting in opposite directions along the length of the bolts. The analytic functions representing the action of the j-th concentrated force on the surrounding rock can be expressed as follows [22]:…”

Section: Two Analytic Functions Considering Bolts Effectmentioning

confidence: 99%

“…Two types of rock bolts can be distinguished [17]: (1) point-anchored rock bolts; and (2) fully grouted rock bolts. In addition, there have been a lot of studies on the anchoring principle of bolts [18][19][20][21][22][23][24][25][26][27][28]. Farmer [24] studied the shear stress distribution of the contact interface and axial force of bolts using the pull-out test.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Analysis of Bolt-Lining Combined Support in Deeply Buried Circular Tunnel

Liu

Cai

2022

Applied Sciences

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The proposal of the NATM has changed people’s understanding of the support principle. Therefore, how to improve the self-supporting capacity of surrounding rock has become an important issue in support research. Bolts and lining are widely used together in various support projects because their bearing and reinforcement effects are in line with the concept of the NATM. This paper puts forward a model to analyze the mechanical behavior of a deeply buried circular tunnel jointly supported by lining and point-anchored rock bolts. Rock mass, lining, and bolts maintain an elastic state and are in full contact with each other. In addition, point-anchored rock bolts are replaced by pairs of concentrated forces of equal magnitude that act in opposite directions. By using the complex function method, the linear equations for calculating the axial force of the bolts and the relevant analytical function coefficients can be established, based on the stress condition of the inner boundary of the lining, the continuity conditions at the interface between the lining and the surrounding rock, and the compatibility condition of the displacement between the bolts and the surrounding rock. Then, using the analytical functions, the stress and displacement of any point in the lining and surrounding rock can be calculated. The results were compared with the numerical solutions. Moreover, the effects of the bolts and the Young’s modulus of the lining on the whole support system are discussed.

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Section: Two Analytic Functions Considering Bolts Effectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanical Analysis of Bolt-Lining Combined Support in Deeply Buried Circular Tunnel

Liu

Cai

2022

Applied Sciences

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Mechanical characteristics and stability analysis of surrounding rock reinforcement in rectangular roadway

Wang

Yang³

2022

Sci Rep

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The stability of surrounding rock with bolt support depends on the stability within the reinforcement range. To understand the reinforcing mechanism of a rectangular roadway bolt fully and accurately, a quantitative method for evaluating the stability of the surrounding rock of a rectangular roadway must be developed. First, a roof beam model of a rectangular tunnel is established according to the deformation law of surrounding rock. Based on the elastic–plastic theory, the deflection calculation formula can be derived, and the ultimate load of the roof beam can be obtained under the plastic state without support. Second, based on the reinforcement effect of bolts, a model of a surrounding rock reinforcement body is established, the physical and mechanical properties of this body are deduced, and a method for evaluating the stability of surrounding rock is derived. Finally, by considering actual engineering cases, the theoretical calculation results of surrounding rock deformation are compared with the numerical simulation and field monitoring results. Moreover, the influence of different parameters of the bolt support on the mechanical characteristics and stability of reinforcement is investigated. The results show that the theoretical calculations approximate the numerical simulation and field monitoring values, thus verifying the rationality of the theory. The physical and mechanical properties and stability of the surrounding rock reinforcement body are considerably affected by changes in bolt length and spacing. The anchor design must apply the following principle: the bolt must either be long and sparsely spaced or short and densely spaced. The theory presented in this paper provides a relatively simple and fast quantitative calculation method for the study of the surrounding rock stability of bolt-supported rectangular roadways.

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Viscoelastic Solution for Axial Forces of Point-Anchored Rock Bolts in a Circular Tunnel

Yao¹,

Cai²,

Lu³

2023

Int. J. Appl. Mechanics

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In this study, a deeply buried circular tunnel supported with point-anchored rock bolts was investigated. Assuming that the effects of each rock bolt on the surrounding rock are simplified to two identical concentrated forces acting in opposite directions, a viscoelastic analytical solution for the axial forces of the rock bolts is presented herein based on the complex variable method and correspondence principle. First, in the solution process, the surrounding rock is considered as an elastic material. A linear equation system for the axial forces was established according to the deformation coordination condition between the surrounding rock and the rock bolts. Second, the surrounding rock was considered as a viscoelastic material. Based on the correspondence principle, Laplace transformation was performed for the equation system of the axial forces to obtain its expression in the Laplace domain, and the values of the axial forces in the Laplace domain could be determined by solving the obtained expression. Finally, the viscoelastic semi-analytical solution for the axial forces was established using the numerical method of the Laplace inverse transformation. The results obtained were also compared with the numerical methods of ANSYS. Accordingly, the effects of the lateral stress coefficient, rock mass Young’s modulus, rock bolt length, viscosity coefficient, and preload on the axial forces of the rock bolts were discussed.

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A theoretical method of mechanical analysis for a circular tunnel reinforced by fully grouted rock bolts

Cited by 5 publications

References 18 publications

Mechanical Analysis of Bolt-Lining Combined Support in Deeply Buried Circular Tunnel

Mechanical Analysis of Bolt-Lining Combined Support in Deeply Buried Circular Tunnel

Mechanical characteristics and stability analysis of surrounding rock reinforcement in rectangular roadway

Viscoelastic Solution for Axial Forces of Point-Anchored Rock Bolts in a Circular Tunnel

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