The dissertation deals with the analysis of mechanisms that cause the wear of disc cutters during rock excavation with tunnel boring machines. In the first part, the wear of a steel disc cutter used in the excavation of a microtunnel was analysed in detail at the macro and micro level. In the second part, a new research method for the wear testing of miniature disc cutters under laboratory conditions was developed. First, we built a special laboratory apparatus for the wear testing of miniature disc cutters on rock samples. Based on the geometric characteristics of the actual disc cutter and its material properties, we then produced miniature disc cutters made of comparable steel for wear testing with a laboratory apparatus. We then conducted a laboratory wear testing of miniature disc cutters on different rock samples that were comparable in their material properties to the rock in which the microtunnel was drilled. In the third part, we performed the same micro-examination of wear on worn miniature disc cutters that we had used to analyse the worn actual disc cutter and identified the wear mechanisms. We found that the changes in micro- and macrostructure that occurred on the miniature disc cutters during the wear testing with the laboratory apparatus on sandstone samples were similar to those on a worn actual disc cutter used in excavating a microtunnel in comparable rock. We demonstrated that the same wear mechanisms occur when disc cutters are used under actual and laboratory conditions. The results of the dissertation contribute to the general understanding of the wear of disc cutters, with a focus on analysing the wear mechanisms. The new research method for laboratory wear testing of miniature disc cutters can be used in the future to predict the wear of disc cutters in practical cases of tunnel construction with tunnel boring machines and to test new materials for the manufacture of disc cutters.
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