The extent of shearing and the integrity of protective sleeve coating of cable bolts

Long term integrity of cables installed around tunnels for ground reinforcement can be influenced by ground movement. This paper reports on the laboratory study of the influence of shearing on damaging the encapsulated plastic sleeves leading to exposure of the cable surface to a hostile environment. Two experimental studies were carried out to assess the extent of shearing displacement and damage to the sleeves. Various shear displacement tests were carried out. In the first test a sleeved cable was encapsulated in a plastic tube and single sheared up to 43 mm vertical displacement and the same procedure was repeated with the second sleeved cable being subjected to double shearing using a double shear testing Machine MKII. In both tests it was found that the corrugated plastic sleeves started to be sheared at a maximum displacement of greater than 20 mm, without damage, it was inferred that the corrugated sleeve can withstand shearing displacement without tearing up to maximum of 33 mm. The experimental procedure and the variation in the testing method are described.