Experimental research on mechanical behavior and bond performance of rock-anchor system subjected to repeated load

In order to study the performance of rock-anchor system under repeated load, two tests were carried out. In the tests, the rock-anchor system was modelled by anchoring steel bar into concrete block; and then repeated load was acted on the system. From the tests, a full relation between load and displacement for the system has been obtained. By using embedded foil strain gauges, bond shear stresses were measured and the distribution of bond shear stress along the bar was achieved. The test results show that both specimens fail in anchor body pulling out from grout body. For the purpose to describe this phenomenon, a load-displacement constitutive relationship with four phases is developed on the strength of previous research. Based on the results, the reasons for bond stress change are discussed; and design recommendations based on critical displacements in different phases are suggested.