Evaluation of EPB TBMs performance

Performance analyses on earth pressure balance (EPB) tunnel boring machines albeit their tremendous impact onproject success, has not been the case of interest for researchers and managers until recent years. In this paper, EPBTBMs performance was discussed under three major subjects: productivity, cost efficiency and ground settlement.Specific Energy (SE) was introduced as an indicator of productivity, and available methods of SE estimation forboth hard rock and soft ground environments were reviewed. It was discovered that although current empiricalformulas are suitable for estimating specific energy for EPB TBMs working in hard rock environments, it wasn’t thecase for soft grounds. Energy consumption and Geological-geotechnical hazards related to TBM tunneling werepresented as factors reducing cost efficiency. Thrust and torque forces account for a majority of energy consumptionand thus it is important to know what are their optimum values. Therefore, analytical equations in order to predictthem were studied. On the contrary, ground conditioning enhances cost efficiency by affecting the two mentionedfactors. Ground conditioners and their effects were briefly evaluated. And finally, ground settlement and archingeffect were assessed, and it was found that chamber pressure and thrust forces are responsible for controlling thesettlement.

Keywords:

EPB TBMS PERFORMANCE , SPECIFIC ENERGY , PENETRATION RATE , COST EFFICIENCY , GROUNDCONDITIONING , GROUND SETTLEMENT