3-D Numerical modeling of joint spacing and orientation effects on TBM cutters

Category Engineering Geology
Group GSI.IR
Location 3rd Iranian rock mechanics conference
Holding Date 10 March 2008
      The performance of tunnel boring machines (TBM) depends on cutters efficiency. Geological conditions and rock mass properties can influence on cutters performance; in this study, a three dimensional numerical modeling based on discrete element method has been used to evaluate the effects of joint orientation and spacing on fragmentation process by TBM cutters. The study modes were, constant spacing with different orientations and constant orientation with different spacing; in the study process three parameters consisting, induced tensile stress, induced shear stress and maximum displacement were calculated. Any stress in each section that may form chips has been saved as critical stress and compared in various joint spacing and orientation in each section to find out critical joint spacing and orientation. Results shows that, firstly critical orientation is an angle in the range of 45 to 60 degrees, where there is a good chance to achieve the maximum rate of penetration, secondary critical and important joint spacing is 200 mm where the effect of spacing on critical stress decreases significantly; furthermore it seems that joint orientation can influence more than joint spacing on rock cutting process.
   Key words: chips, tunnel boring machine (TBM), cutters, joint spacing, joint orientation.

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