Abstract
Jointed rock masses are frequently encountered during the TBM excavation. To investigate the rock breakage mechanism of jointed rock mass by disc cutter and precursory information before rock failure, a series of indentation tests were performed on shear rheological test system. During the test, breaking process of specimens were recorded by digital image correlation system and thermal infrared imager simultaneously. Therefore, the strain fields and thermal infrared images of jointed rock mass by disc cutters were obtain. The experimental results show that the failure process of jointed rock mass can be divided into four stages: compaction stage, linear elastic stage, residual failure transition stage and post-failure stage. Besides, the characteristic of strain fields shows a good accordance with that of infrared radiation temperature fields at each stage. The failure of rock samples is dominated by shear failure, and the localized temperature rise is an important infrared precursor of rock fracture and instability. The experimental results are of great significance to the deep understanding of the breaking mechanism of jointed rock mass and warnings of engineering disasters.
Highlights
The full-face Tunnel Boring Machine (TBM) is widely used in the construction of urban subway for its high efficiency and little disturbance to the surrounding environment
The failure process of jointed rock mass can be divided into four stages: compaction stage, linear elasticity stage, residual failure transition stage and post-failure stage
Indentation test was performed on the jointed rock mass
Summary
The full-face Tunnel Boring Machine (TBM) is widely used in the construction of urban subway for its high efficiency and little disturbance to the surrounding environment. As the joint conditions encountered during the tunnelling have a significant impact on the penetration rate of TBM, it is of great significance to reveal the mechanism of rock breaking. Instability of surrounding rock during the tunnelling is frequently encountered. Investigation on the abnormal precursors of jointed rock masses is essential. In order to study the rock breaking mechanism of cutter, Gnirk et al.[1] and Maurer et al.[2] analyzed the failure characteristics of rock mass in the test of cutter penetration. The minimum and average infrared radiation temperature of the rock specimens were analysed. It was found that the evolution law of infrared radiation temperature was closely related to the process of rockburst inoculation and occurrence. Song et al.[7] quantitatively studied the evolution characteristics of strain field and strain localization during the failure
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