1. Determination of rockburst reduction coefficient [formula omitted] in the modified rock mass classification system for TBM tunnels and tunneling.
- Author
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Lu, Jianwei, Gong, Qiuming, Wei, Junzheng, Han, Bei, and Yin, Lijun
- Subjects
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TUNNELS , *WATER tunnels , *TUNNEL design & construction , *BORING & drilling (Earth & rocks) , *ROCK music , *CLASSIFICATION , *DATABASES - Abstract
The modified rock mass classification system for TBM tunnels and tunneling was proposed to assess rock mass quality, rock mass boreability, and TBM construction suitability. However, the section concerning the impact of adverse geological conditions on TBM utilization was not yet finalized. In this study, the classification system was upgraded to the stressed hard rock tunnels by adding the coefficient. A database comprising 551 instances of rockbursts and their corresponding TBM performance data was compiled from the Yinhan Water Conveyance Tunnel in China. The characteristics of rockbursts occurring in the tunnel excavated by TBM and their formation mechanisms were introduced. The depth of damage to the tunnel wall was used as the assessment index for the intensity grade of rockbursts. Quantitative relationships were established between the intensity grade of rockbursts and TBM performance parameters for the first time. As the intensity grade of rockbursts increased, there was a substantial reduction in TBM utilization, while the penetration rate exhibited no significant changes. The reduction coefficient β A for TBM utilization at the rockburst intensity grades, namely minor damage, moderate damage, and severe damage, was determined to be 0.88, 0.60, and 0.39 respectively. These coefficients were subsequently integrated into the classification system. Finally, a simple case was presented to illustrate the applicability of the rockburst reduction coefficient β A and the upgraded system. • The database was established with different grades of rockburst data. • Rockburst impact on rock mass boreability, stability, and TBM process was analyzed. • The quantitative relationships between rockburst and TBM parameters were obtained. • The rockburst reduction coefficient β A on TBM utilization was determined. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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