Problems concerning cutting tool performance during TBM work: modelisation and testing of the rock under the action of the tool

In rock excavation engineering, cutting performance prediction plays an important role in machine and cutting tool design. In the past, experimental and theoretical studies on the interaction between rock and TBM tools were conducted for the explanation of the intimate mechanism of rock failure and to obtain knowledge that was able to improve the performances of the TBMs. Nevertheless,, despite several decades of academic rock mechanics and practical rock engineering, there is still a lack of some fundamental knowledge on rock-tool interaction. The objective of this paper is to evaluate a model that predicts the distributed displacement and stresses under a TBM disk, taking into account, in the failure mode, the constitutive law of the rock, the presence of the tunnel head, the amount of the natural stress due to the high overburden, and the forces caused by the TBM disk on the tunnel head. Some laboratory tests were also planned to validate the theoretical results.