Numerical study to estimate the cutting power on a disc cutter in jointed rock mass

Abstract

The Linear Cutting Machine (LCM) test is known to be a reliable method for designing disc cutters by estimating the penetration performance of a Tunnel Boring Machine (TBM). The LCM test is a laboratory test that uses large-scale rock blocks to estimate the real-scale load on disc cutter; the LCM test offers many advantages, but the costs of preparing the rock samples and performing the laboratory test are too high. In addition, the test results from jointed rock blocks are rarely trustworthy because of the difficulty of performing the LCM test with this type of rock sample. To compensate for the failings of the laboratory test, many studies have been conducted to develop a suitable numerical model. However, few studies have investigated the mechanism of rock fragmentation as a function of the joint spacing and the joint direction. This paper presents the results of a Discrete Element Analysis (DEA) of the cutting power exerted on a TBM disc cutter at various joint dip angles, dip directions and spacings. The results show that the cutting power must be increased when the disc cutter advances in a direction opposite to the joint dip. The numerical analysis also shows that the cutting power of a disc cutter increases as the joint dip angle decreases and the joint spacing decreases. Comparing the relationship between the cutting power of the disc cutter and the distribution pattern of the rock joints with the LCM test results can be used to increase the reliability of TBM performance predictions.