Stabilisation of the Excavation Face in Shallow Tunnels Using Fibreglass Dowels

• Published in: Rock mechanics and rock engineering Vol. 45; no. 4; pp. 499 - 517
• Main Authors: Oreste, P. P., Dias, D.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.07.2012; Springer; Springer Nature B.V
• Subjects: Applied sciences; Buildings. Public works; Civil Engineering; Design engineering; Drilling & boring machinery; Earth and Environmental Science; Earth Sciences; Exact sciences and technology; Excavation; Fiberglass; Geophysics/Geodesy; Geotechnics; Mathematical analysis; Original Paper; Reinforcement; Rock; Rocks; Safety factors; Stabilization. Consolidation; Tunnels; Tunnels (transportation); Tunnels, galleries; Face reinforcement; Limit equilibrium method; Safety factor; Shallow tunnel; Fibreglass dowels; Stability; Stabilization; Excavations; Three dimensional model; Stud; Reinforcement; Tunnel driving; Glass fiber; Equilibrium method; Computing method
• ISSN: 0723-2632; 1434-453X
• DOI: 10.1007/s00603-012-0234-1

Stability of the excavation face in shallow tunnels excavated in poor rock is at present a relevant problem in tunnelling. Even though face reinforcement with fibreglass dowels has proved to be efficient, there is still no reliable routine design method available. A new calculation procedure is illustrated in this paper for the analysis of face reinforcement with fibreglass dowels in shallow tunnels. The procedure is based on the limit equilibrium method applied to the rock core ahead of the face, and it offers a detailed evaluation of the interaction between each reinforcement element and the surrounding rock. The main calculation result concerns the safety factor of the excavation face with dowel reinforcement. On the basis of this safety factor, it is possible to identify the appropriate dowel lengths and the number of dowels. The procedure has been applied to two real cases, and satisfactory results have been obtained.