description is presented on the interaction between a reinforced drift and the surrounding rock. It attempts to explain the support mechanisms and characteristics of cement grouted rock bolts, as used in hard rock mining and underground construction. A 20 m long section of a test drift at the 514 m level in the Kiirunavaara Mine, was instrumented with 20 rock bolts mounted with strain gauges and linked to a data logger, and 50 bolts combined with single-anchor extensometer. Rock movements were measured with 23 borehole extensometers, 45 convergence measurement stations, and precise levelling. 14 stress monitors recorded changes in the tangential stresses in the surrounding rock mass.