A simple analytical procedure that applies classical beam-column theory for evaluating passive rock bolt roof reinforcement is presented in this paper. The analytical model is derived from first principles and is capable modelling any number of reinforcing bolts. Each rock bolt is modelled as a linear spring and the model allows for non-uniform bolt spacing. In this study the rock beam is assumed to be isotropic and linearly elastic for the sake of simplicity. However, the analytical model can be extended to include anisotropic rock mass as well as inelastic material behavior. The solution to the couped set of governing equations is obtained by using a simple numerical solution procedure. The results from the analytical model indicate that the critical buckling load of a rock beam is strongly influenced by the ambient rock modulus. For salt-rock excavations the rock modulus typically declines with time due to various phenomena, and a diminished modulus could seriously compromise roof stability The other main conclusion of this study is that rock bolts lose their effectiveness in restraining a roof beam once its critical buckling load is approached. In such a situation, increasing bolt stiffness does not improve its reinforcing on a roof beam but it enhances the possibility of bolt failure due to anchor pull-out. © 1997 by John Wiley & Sons, Ltd.


Mechanical and Aerospace Engineering

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Keywords and Phrases

Beam-column; Euler-Bernoulli; Pull-out; Rockbolt; Roof-reinforcement; Stability

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Document Type

Article - Journal

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Publication Date

01 Jan 1997