A numerical investigation of side force variation on disc cutters in mechanized tunnel boring machines

Document Type : Original Research

Authors
M. Sabri 1
H. Vahidi 2
A. Zonoubi 3
M. Rostami 4
M. Houshang 5
1 Tarbiat Modares university
2 Olomtahghighat University
3 Emma Hosain university
4 Islamic azad university
5 Sanati Sharif University
10.22034.24.3.59
Abstract
As the use of mechanized tunnel boring machines (TBMs) increases, the performance of these machines has become increasingly important for researchers to work on. Disc cutters, as one of the main components of the cutter head, are responsible for transmitting the thrust force to the rock and breaking it. Studying the rock-cutting process by TBM disc cutters is vital to mechanized tunnel excavation. For this reason, this issue has been widely studied by researchers in recent decades. The shape and layout design of the cutter head, disc cutters spacing, and the size and shape of cutters are the adjustable factors in improving the efficiency of rock cutting and TBM excavation. It is important to determine the forces acting on the disc cutters in mechanized tunnel boring machines because these forces are used in the design. A review of the history of studies shows that lateral forces have been studied much less than other forces. Therefore, in this article, a numerical study of the side forces on the disc cutters and their relationship with the installation radius and the tip width has been studied. Furthermore, the information of lot 2 Kani Sib water conveyance tunnel has been used to validate the results. For this, numerical simulations have been conducted with three types of 17-inch disc cutters in installation radii of 0.3 m, 1 m, and 2 m with tip widths of 18.5 mm, 19.6 mm, and 20.8 mm. The results of the numerical models show that the side forces acting on the central disc cutters with low installation radius are much higher than others. Additionally, these forces are mainly asymmetrical and become symmetrical as the installation radius increases. Central disc cutters are subjected to unbalanced and asymmetric forces because of the excessive side force. This will cause the disc cutter bearing system to malfunction and increase costs significantly. A decrease in the balance of the cutter head and increased vibrations are other consequences. Increasing the tip width aggravates this condition. The damage pattern of the disc cutters in lot 2 Kani Sib tunnel confirms this conclusion. According to this project, more than 74% of central cutters' failures with low installation radius are related to bearing problems. This type of failure is caused by large asymmetric side forces, while only 26% of the face disc cutters with a large installation radius failed in this way, which confirms the results of the numerical models.

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Subjects

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Modares Civil Engineering journal
Volume 24, Issue 3
July and August 2024
Pages 59-69