Rock anchors are high-capacity reinforcement measures used to stabilise large-scale infrastructure. There are four main failure mechanisms for rock anchors, which are: (1) rock mass uplift failure; (2) grout-rock interface failure; (3) tendon-grout interface failure; and (4) steel tendon tensile failure. A large-scale laboratory test rig has been developed to test block models which simulates rock mass uplift failure (failure mode 1). The design methods against failure mode 1 are the most conservative and least satisfactory design methods according to literature. The full-field displacements of the models were monitored with digital image correlation (DIC). The block model tests had higher capacities than what was calculated with the current design methods using the weight of overlying rock cone and presumptive shear strength values along the assumed failure cone. The capacity and failure shape in the block models showed to be structurally dependent on the block model pattern. The horizontal stress in the models increased during the tests, which showed that load arches were induced in the block models during the uplift. The load capacity of the block models increased with model height and horizontal stress level.
KEYWORDS
Block model, anchor pullout, load arching, failure mode, influence of joint pattern.
