Comparative Testing of Cable Bolt and Wire Rope Lacing Resistance to Static and Dynamic Loads

Abstract

the conduction of mining activity under the conditions of rock bursts and rock mass tremors means that designers often utilise support systems comprising various configurations of steel arch, rock bolt and surface support. Particularly difficult geological and mining conditions, when wire mesh does not provide sufficient dynamic resistance, it requires an additional reinforcement with wire rope lacing in the form of steel ropes installed between the bolt ends and fixed to them by means of various rope clamps (e.g. u-bolt clamps). Bench tests were conducted to compare the strength of wire ropes under static and dynamic loading. the tests involved wire ropes with an internal diameter of Ø15.7 mm. tests under static loading demonstrated that the cable bolts transferred a maximum force F s max = 289.0 kn without failure, while the energy absorbed until failure was E 1 s = 16.6 kj. A comparative test result analysis for the wire ropes used in the bolt designs revealed that the influence of dynamic loading forces has a significant effect on reducing the rope load capacity, which results in the brittle cracking of the wires in the rope. Although the average dynamic force leading to wire rope failure F d max = 279.1 kn is comparable to the minimum static force F min = 279 kn defined in the relevant standard, the average energy E 1 d absorbed by the cable bolt until failure is 48% lower than the energy E 1 s determined for wire rope failure under static loading. Furthermore, cable bolt failure under dynamic loading occurred at an impact velocity of the combined ram and crosshead masses ranging within v p = 1.4-1.5 m/s.