Abstract
The construction of large-span caverns in hard rock in a major underground storage project is discussed in this paper. In-situ stresses were measured using hydraulic fracturing and 3-D over coring during construction, showing a horizontal stress ratio of 2-3 times the vertical stress. Rock reinforcement design was based on the Q-system combined with numerical modelling for special design cases. Tunnel performance were checked and monitored by in-situ instrumentation, including deformation, convergence, and bolt load. A measuring borehole was drilled into the virgin rock before rock excavation, which provided a direct and very insightful comparison with various deformation measurements made during rock excavation. It has proven that the high horizontal stresses are very favourable to stability of the opening.
Original language | English |
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Journal | International Journal of Rock Mechanics and Mining Sciences |
Volume | 41 |
Issue number | SUPPL. 1 |
DOIs | |
Publication status | Published - 1 May 2004 |
Externally published | Yes |
Keywords
- Horizontal stress
- Large-span tunnel
- Site monitoring
- Stability