Experimental Study on Excavation Characteristics of Donut Type TBM

Abstract

A donut type TBM, which has an opening at the center of its cutter head, is proposed as a hard rock TBM (full-face type TBM). The proposed donut type TBM, has various mechanical excavation characteristics that are different from those of conventional full-face type TBMs, including elimination of center cutters due to the center of the face not being excavated and reduction in the number of cutters installed as a result of reduction of the area excavated. In this study, in order to evaluate these excavation characteristics, new experimental equipment that excavates the entire area that comes into contact with the cutter head was produced and used to excavate a high-strength mortar specimen. The excavation experiment using this equipment reproduced TBM's rock breakage mechanism and demonstrated that the center cutters cause an increase in the cutting resistance. The study including the experiment showed that the donut type TBM has a greater excavation speed, which leads to a decrease in a specific energy.