Ratchapon Mingkhwan, Thanittha Thongprapha, Laksikar Sitthimongkol and Kittitep Fuenkajorn, Geomechanics Research Unit, Suranaree University of Technology, University Avenue, Nakhon Ratchasima 30000 Thailand
The objective of this study is to investigate the effect of rock joints on the CERCHAR abrasivity index (CAI). Sandstone, limestone, and basalt with parallel fractures with joint numbers varying from 1, 2, 3, to 4, and joint apertures of 0, 0.3, 0.5, to 0.8 mm are tested. The joint spacing is kept constant at 2 mm. The results indicate that the CAI value decreases with increasing joint frequencies and apertures. The ploughing force exerted on the stylus pin is reduced when the pin tip reaches the fracture. This becomes more pronounced as the aperture becomes larger. As the number of joints increases and the separations widen, greater scratching force is increased. The ploughing volume increases as CAI decreases, suggesting that highly fractured rocks show less CAI and less energy to cut while yielding a higher ploughing volume as compared to rock with less fractures.
joint number, joint separation, ploughing force, ploughing volume.
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