Analysis of the Effect of the Tool Shape on the Performance of Pre-Cutting Machines during Tunneling Using Linear Cutting Tests

Abstract

Owing to several advantages, mechanical pre-cutting techniques were first introduced in the United States and subsequently used in Europe for tunneling. Pre-cutting machines perform mechanical excavation tunneling using cutting tools such as tunnel boring machines (TBMs) and roadheaders. Linear cutting tests are reliable and widely used to predict the performance of TBMs and roadheaders. In this study, the effect of the cutting tool shape of a pre-cutting machine was analyzed using linear cutting tests. Assuming the basic shape of the tool, the clearance and rake angles of the tool were designated as variables that determine the shape. The experimental results for samples with different mechanical properties were analyzed considering the cutting force, cutting volume, and specific energy, which were inversely related to the clearance angle. Initially, the force decreased significantly as the clearance angle increased from 0 degrees to 5 degrees, and then converged at angles of 10 degrees and higher. However, the cutting volume decreased linearly with angles. The specific energy behaved similarly to the force. Compared with the clearance angle, the rake angle slightly affected the cutting force, volume, and specific energy. When the rake angle increased from 0 degrees to 5 degrees, the cutting force and volume decreased slightly; however, both increased after 5 degrees. The specific energy exhibited a similar trend.