ABSTRACT
The article consists of the short outline of the state, application, designing, analysis and instrumentation of rock bolts and cable anchors in Yugoslavia, used for an improvement of rock masses in underground construction as well as in securing slopes, cuts and notches. The progress in application of anchors asks for an answer in distribution of main, normal and shear stresses respectively upon the perimeter between steel and grouting mix and grouting mix and rock. For more correct determination of normal and shear stress distribution upon anchoring length it is necessary to possess reliable data of laboratory and in situ tests. Satisfactory results of instrumentation of test model anchor, carried out in laboratory condition have made possible the instrumentation of anchors in site conditions. The measuring results of test model anchor compared with results of numerical analyses point to the fact that linear elastic anchor model, grouting mix and concrete, rock mass respectively do not give the satisfactory results due to the redistribution of stresses which is a result of ultimate stress value exceeding in single elements along the anchoring length.
