Introducing a Model for Road headers' Performance Prediction Based on the Specific Energy and the Angle between Tunnel Axis and the Planes of Weakness
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Abstract :
Road headers offer a unique capability and flexibility for the excavation of soft to medium strength rockformations, hence; are extensively used in underground mining and tunneling operations. A critical issue insuccessful road header application is the ability to evaluate and predict the machine performance. The mainobjective of this research study is to investigate the cutting performance of road headers in coal measure rocksby paying special attention to the influence of discontinuity orientation (alpha angle) and the specific energy.With this respect, a database was established from detailed field data including the measured instantaneouscutting rates (ICR) and geomechanical parameters of the coal measure rocks for each cutting condition throughthe tunnels in Tabas coal mine project. The database was then analyzed by utilizing the statistical method inorder to yield new predictive models. The influence of alpha angle (the angle between tunnel axis and the planesof weakness) on road header performance was investigated and the correlation between them was found to begood (R²=0.96). The analysis of the specific energy also showed that there is a relatively good relation (R²=0.91)between this parameter and ICR. Finally, the new predictive models for ICR (with respect to alpha angle andspecific energy) showed to have highly correlated relationships within the limits of measured values and hencemay successfully be used to evaluate the performance of medium-duty road headers in coal measure rocks.
