The mechanical and cutting properties of rocks related to the application of tunnel boring machines

Abstract

Tunnelling for what ever purpose, -has occupied mankind since the beginning of time. Tunnels for protection, tunnels for secret access to forbidden places, tunnels for the extraction of minerals and tunnels for speedier transportation have been gouged through every form of strata. For centuries the task of boring below ground was performed by rudimentary tools, and it was not until a scant 110 years ago that the first successful attempt was made at mechanising the process. It is recognised that machine tunnelling has several advantages over the conventional drilling and blasting method as:- 1. Greater safety 2. Less overbreak 3. Less labour required 4. Continuous excavation and muck removal 5. No blasting damage to nearby structures 6. Potentially faster rate of excavation. However, much more research and development work is needed to make the tunnelling machine more versatile, reliable, and economical than they are today. The research should concentrate on the following problems: - 1. Capital cost is high 2. Boring in harder rocks 3. Dust control 4. Cutter wear S. Muck removal 6. Tunnelling in zones of high water flow 7. Tunnelling in zones of defective rock 8. Prediction of machine performance in advance of construction 9. Bearing wear 10. Alignment of bore ll. "Change of diameter.! In this work the prediction of machine performance in advance of construction was carried out, 'using the standard rock cutting test as a primary factor and the. other rock properties as the relevant factors. These tests were conducted using the core samples obtained from the preliminary boreholes along the two proposed tunnelling projects, namely the Tyne-Tees aqueduct tunnel and the Tyneside Rapid Transit tunnels.