It is proposed to construct a 3m diameter, 50m long tunnel, heading 0950, through the andesite lava flow at Maori Bay (Muriwai). As part of the preliminary investigations you have been asked to write a report assessing the suitability of the rock mass for this project, & provide an initial indication of rock suitability (including stand-up time) & support that will be required in the tunnel.
Attached is a sheet from a preliminary defect survey carried out on the exposed face of the lava flow.
1. Describe the local geology (Maori Bay - Muriwai)
- i.e. rock types & structures, etc at and around the site
- Find formation & group names from an appropriate geological map or publication
2. Represent the defect survey graphically (not in a table)
3. Estimate stand-up time using the RMR System (showing workings)
4. Comment on the ease & possible methods of excavation of the tunnel
5. Identify possible methods for tunnel support (if any is needed) as given by the RMR system
6. Your report should also contain:
7. A map showing the location of the site
8. An estimate of rock material (compressive) strength of the lava flow
9. An estimate of what the RQD would be in a horizontal bore hole (showing workings)
10. A list of all references used. These must be cited in the report using the APA System