Investigation of rock breaking mechanism with TBM hob under traditional and free-face condition. (1st February 2021)

• Record Type: Journal Article
• Authors: Zhang, Xuhui; Hu, Dingbang; Li, Jianmin; Pan, Jiaji; Xia, Yimin; Tian, Yanchao
• Is Part Of: Engineering fracture mechanics. Volume 242(2021)
• Publication Date: 2021-02-01
• Subjects: Rock breaking performance -- TBM hob -- Traditional condition -- Free-face condition; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2020.107432
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: Cutting rock by TBM hob under free-face condition is explored and the rock breaking mechanism between traditional condition and free-face condition are compared. The generation process of rock chip, rock breaking force and rock breaking efficiency of TBM hob under two cutting conditions are investigated. It is proved that cutting rock under free-face condition can reduce rock breaking forces and enhance rock breaking efficiency significantly compared with traditional condition. Abstract: To compare the rock breaking mechanism of the tunnel boring machine (TBM) hob under traditional condition and free-face condition, a series of rock cutting tests and rock cutting simulations of the TBM hob under two cutting conditions are conducted. The rock chip, rock breaking forces and rock breaking efficiency etc. are investigated in this study. The research results denote that the rock chip size under the free-face is far larger than that under the traditional condition. Both the rock breaking forces and the rock breaking efficiency under the free-face condition could be reduced and be enhanced respectively compared with that under the traditional condition when the value of St and Sf ranges from 20 mm to 80 mm. Furthermore, the numerical and theoretical results also confirm the cutting rock under the free-face condition is promising, which can be applied to the water-jet TBM and the two-stage cutterhead TBM to improve the rock breaking performance of the TBM hob significantly.