Pull-out and Critical Embedment Length of Grouted Rebar Rock Bolts-Mechanisms When Approaching and Reaching the Ultimate Load

Abstract Rock bolts are one of the main measures used to reinforce unstable blocks in a rock mass. The embedment length fully grouted stable and competent stratum behind is an important parameter determining overall bolt length. It required that section must be longer than critical ensure will not slip when loaded. Several series pull tests were carried out on rebar evaluate pull-out mechanics bolts. Bolt specimens with different lengths water/cement ratios installed either concrete block cubic meter or steel cylinders. Load displacement was recorded during testing. For some loaded beyond yield load, permanent plastic deformation also recorded. Based test results, three types failure mechanisms identified, corresponding loading conditions: (1) below strength steel; (2) between ultimate loads, is, strain hardening (3) at load. 2 3, it found included components: elastic length, completely debonded due formation cone borehole collar.