Tweet Share

• Send by email

  Send by email

  

  Unexpected performance and cost factors for hard rock TBM. Analyses of specific cases with the thrust-penetration gradient

  In the common view of tunneling experience, discontinuities are considered with downscaling effects on the mechanical properties of rock mass. The effect of discontinuities in mechanized hard rock excavation is of ambivalent nature. The presence of favorable number and orientation of joints leads in general to a reduced effort for TBM excavation and higher advance rates; where else the same presence of joints may indicate an instable face and blocky ground conditions. In this context the amount and orientation of the in-situ stress is an important aspect, which has to be considered. Recent experience in various TBM projects in Europe support this rule of thumb. Adverse experience was gained with hydrothermal activities along shear zones, which showed decreasing TBM advance rates. The reduced performance and higher effort of chipping of the cutters was investigated with full-face laser scanning methods in order to investigate the chipping process under in-situ conditions.

  Recipient :

  Name ^* :

  E-mail address ^* :

  ^* Required fields

  Send   or  Cancel

• Print