Rock Hardness Index Properties and Geotechnical Parameters for Predicting Tunnel Boring Machine Performance,

摘要

To bid a tunnel to be excavated by machine, a contractor must have reliable estimates of expected excavation time,cutter costs and overall feasibility. To assist in making such predictions, a series of rock index tests has been proposed,developed and related to boreability. The proposed index properties and other variables were evaluated by empirically relating selected rock properties to TBM penetration rates from recently machined tunnels. Samples were drilled from machine bored tunnel walls,tested parallel to the direction of machine penetration rates from recently machined tunnels. Samples were drilled from machine bored tunnel walls,tested parallel to the direction of machine penetration,and the results were compared to rates of penetration at respective sampling locations. Results indicate that the series of rock hardness index properties investigated in this study can be related to TBM penetration rates. With certain limitations and qualifications,acceptable empirical relationships have been developed between in situ Schmidt Hammer Hardness and unconfined compressive strength.