Extrusion movements of a tunnel head reinforced by finite length bolts-a closed-form solution using homogenization approach

• Published in: International journal for numerical and analytical methods in geomechanics Vol. 24; no. 6; pp. 533 - 565
• Main Authors: Wong, Henry, Subrin, Didier, Dias, Daniel
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.05.2000; Wiley
• Subjects: analytical solution; Applied sciences; bolts; Buildings. Public works; composite; Computation methods. Tables. Charts; elastoplasticity; Exact sciences and technology; homogenization; Structural analysis. Stresses; tunnels; Tunnels, galleries; Constitutive equation; Strengthening; Script; Homogenization; Bolt; Verification; Composite material; Parametric method; Elastoplasticity; Analytical method; Extrusion; Numerical simulation; Stiffness; Tension; Tunnels
• ISSN: 0363-9061; 1096-9853
• DOI: 10.1002/(SICI)1096-9853(200005)24:6<533::AID-NAG80>3.0.CO;2-8

An analytical model on the general behaviour of a tunnel head, reinforced by finite length bolts is proposed. This model is based on the homogenization method and spherical symmetry assumption. Despite its simplicity, and in consequence its limits of validity, it does allow a quick estimation of the key design parameters: frontal displacement, extension of decompressed zone, ground stresses and bolt tension, and constitutes thereby a very useful and handy tool for design engineers. In particular, the influence of the reinforcement length, as well as other important design parameters, are studied by the proposed model. The charts resulting from the parametric studies are directly applicable. Otherwise, the comparison to a 3D numerical model is also presented in this paper. The first results provide the validation of the analytical solution, at least in terms of average extrusion movements. Copyright © 2000 John Wiley & Sons, Ltd.