Distinct analysis of fully grouted bolts around a circular tunnel considering the congruence of displacements between the bar and the rock

• Published in: International journal of rock mechanics and mining sciences (Oxford, England : 1997) Vol. 45; no. 7; pp. 1052 - 1067
• Main Author: Oreste, P.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-10-2008; Elsevier Science
• Subjects: Applied sciences; Buildings. Public works; Computation methods. Tables. Charts; Congruence of displacements; Deep and circular tunnel; Exact sciences and technology; Finite difference method; Fully grouted bolts; Radial bolts; Structural analysis. Stresses; Tunnels, galleries; Congruence of displacements; Radial bolts; Fully grouted bolts; Deep and circular tunnel; Finite difference method; Congruence; Radial distribution; Stress strain relation; Deep tunnel; Bolt; Circular section; Displacement; Dimensioning; Grouting; Reinforcement; Numerical simulation; Computing method
• ISSN: 1365-1609; 1873-4545
• DOI: 10.1016/j.ijrmms.2007.11.003

This paper presents a new calculation procedure for the analysis and dimensioning of fully grouted radial bolts in tunnels. This procedure is based on the principle of congruency of the displacements, imposing the conditon that the lengthening of the bolt, added to the displacements due to the shear strains in the bolt–rock interface, is equal to the expansion in the radial direction of the reinforced rock annulus. A comparison of the results obtained using this procedure with those obtained using the traditional numerical modelling method, which is more costly in computational terms, has led to satisfactory results.
The application of the procedure to a real case has given results that are comparable with the in situ measurements. The proposed instrument is able to analyse the stress and strain state in rock in detail, in the presence of a bolting intervention, and to proceed with its correct dimensioning with the objective of improving the degree of stability of the rock around the tunnel.