Determination of stress distributions on the fully grouted rock bolts

The purpose of this study is to determine the deformation behavior and load-carrying capacity of fully grouted rock bolts. Pull-out tests are carried out to determine the failure mechanism and intrenchment effect of rock bolts. The parameters such as bolt strength, grout strength, rock strength, applied loads and deformation behavior of the parameters are taken into consideration in tests.For this purpose, stress distributions along the rock bolts which are placed around the excavation cavity (tunnel) and the secondary stresses arisen from therein and the resulting deformations are to be determined. Also, the width of the plastic zone assumed to develops around the tunnel is determined indirectly.Grouted rock bolts work with rock mass. Therefore, the legth changes of bolt body is also equal to the deformations that occur in the rock mass. The length changes of rock bolts due to stresses will be determined in this study. In practice, contrary to this procedure, secondary stresses developed around the tunnel are calculated from the length changes of rock bolts. Depending on calculated secondary stresses, the required reinforcement element amount which is necessary for safe, stable and economical tunnel construction can be determined.