The mechanism of rock fragmentation by disc cutters during tunneling is the key to influencing the TBM (Tunnel Boring Machine) performance. In order to study the characteristics of the rock fragmentation process, various numerical methods were performed to establish the three-dimensional model. In this paper, three disc cutters are regarded as the research object, and accordingly three basic collaborative rock fragmentation patterns are proposed to analyze the collaborative effects of disc cutters on the rock fragmentation process, including the sequential cutting pattern, the inside-out cutting pattern and the outside-in cutting pattern. Also, the numerical models of three 19-inch disc cutters are established using the ABAQUS software, considering three different cutting patterns. The center cutters, the plane cutters and the gauge cutters are all considered in this numerical simulation due to their different rotating radius and installation angles, and the model also takes several different rock types into account to consider the stratum influence. The specific rock parameters are collected from the rock samples in Yinhanjiwei Water Conveyance Project. By means of simulating the rotating cutting motion of three rock fragmentation patterns, the mechanical parameters and the specific energy of the disc cutters are analyzed to obtain the best cutting pattern. The results show that the inside-out pattern is one of the most ideal patterns in rock fragmentation process. Furthermore, the results of simulations are verified by the Linear Cutting Machine tests, and can provide some reasonable suggestions for the optimization of the disc cutters layout design of TBM.

1. Introduction

The tunnel boring machine (TBM) has been widely applied to tunnel constructions like the subway, the railway, the highway and the water conservation projects, due to its rapid advance rate, high efficiency, nice tunnel formation, little impact on the surrounding environment and excellent working safety (Zhao, 2007). The TBM tunnel excavation depends on disc cutters which are installed in the cutterhead to cut rocks. The performance prediction and rock fragmentation mechanism by TBM cutters are becoming considerably important issues. Research aims to study the rock fragmentation mechanism of TBM cutters and to instruct the optimization of the layout pattern of TBM cutters.

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