Foreign experience in using wedge disk rolling cutters for equipping tunneling shields

In the foreign practice of designing and operating tunneling shields, it is now customary to equip the tunneling systems with large diameter CCS type disk rolling cutters. However, there is another type of disk rolling cutters for rock breaking, wedge disk rolling cutters, which, as practice shows, in some situations can provide higher work efficiency than the standard tool. Domestic researches in this field comes down mainly to the study of wedge disk rolling cutters of relatively small diameter for equipping boom ripper tunneling machines. However, this experience cannot be applied to the operation of tunneling systems; therefore, the study of foreign experience on this issue is advisable. This paper presents analysis of comprehensive studies conducted by foreign experts in the construction of various purpose tunnels in Turkey in the first decade of this century. These studies include determining wide range of physical and technical properties of rocks, performing laboratory and field tests to determine power characteristics of the rock breakage process, comparing laboratory, field and theoretical calculated values of power and energy performance of tunneling systems. Based on findings of the tests it was found that rock breakage efficiency is determined not only by the rock strength, but also by its structural and texture features. Differences were observed when comparing the laboratory experiment data with the field data, and when comparing the laboratory and field values of disk rolling cutter cutting force in the process of rock breakage with the theoretically calculated values. In addition, breakage of viscous non-abrasive rocks with small amount of mineral inclusions or, with certain reservations, breakage of very strong and abrasive rocks should be referred to promising applications for wedge frontal disk rolling cutters. Not all conclusions made on the basis of the analysis coincide with the opinions of the authors of the initial studies, therefore, for more complete understanding of the topic, it is recommended to read the literature (especially foreign one) included in the list of cited sources.

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