Performance of D-Bolts Under Dynamic Loading |
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Authors: | Charlie C Li Chantale Doucet |
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Institution: | (1) Department of Geology and Mineral Resources Engineering, The Norwegian University of Science and Technology, Trondheim, Norway;(2) CANMET Mining and Mineral Sciences Laboratories, Natural Resources, Ottawa, Canada |
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Abstract: | In this work, dynamic test results of D-bolts are presented. The rock bolt specimens studied are 20 and 22 mm in diameter
and 0.8–1.5 m in section length. The bolts were tested at an impact velocity of 5.4–6.2 m/s and with impact energy varying
from 10 to 60 kJ. In total, over 50 drop tests were conducted during a period of three years. The dynamic tests show that
a D-bolt section of 22 mm × 1.5 m can sustain an impact of 56 kJ of a dynamic impact and absorb 60 kJ of energy prior to failure.
The maximum impact energy of the 22 mm bolt is thus 37 kJ/m of bolt and the maximum energy absorption is 40 kJ/m. The displacement
of the D-bolt increases linearly with the impact energy. A theoretical solution has been obtained for the relationship between
the impact energy and the displacement of the bolt. It states that the energy absorption of a D-bolt section is proportionally
related to the volume of the bolt section and the tensile strength and ultimate strain of the bolt material. It was also found
that the magnitude of the impact energy determines whether or not the bolt fails, while the impact momentum determines how
long the impact lasts. The impact duration increases linearly with momentum as long as the bolt shank does not fail. |
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