Recently, the dual mode TBM twins 'Yong'an' and 'Huasui Fenjin', jointly developed by China Railway Engineering Equipment Group Co., Ltd. under CRHIC, rolled off production line in Zhongshan and Shunde, Guangdong Province successively. They will be used to construct Guifengshan Tunnel of Zhuhai-Zhaoqing HSR Jiangji Section, a key project of Guangdong-Hong Kong-Macao Greater Bay Area.

'Yong'an', the earth pressure/TBM dual-mode shield machine has excavation diameter of 14.29m. Along the excavation section measuring 3,963.5m, it has to pass through strongly weathered gneiss and slightly weathered gneiss, and underpass three existing lines of viaduct, Pearl River Delta Ring Expressway and Guangzhou-Zhuhai Railway. 'Huasui Fenjin' has excavation diameter of 14.29m. Along the shield tunneling section of 4.78km, it has to pass through strongly weathered argillaceous siltstone, slightly weathered sandstone and slightly weathered granite, as well as structural fault zone, joint intensive zone and other unfavorable geology, which set high requirements for TBM performance and ground surface settlement control.

'CRES 740' successfully completed the conversion from TBM mode to earth pressure mode at Fuzhou Metro Line 2 on March 25. China Railway Engineering Services Co. Ltd. (CRES) affiliated to CRHIC is responsible for its maintenance and mode transition. This mode conversion has provided valuable experience for the subsequent mode conversion of its kind.

For Fuzhou Metro Line 2 East Extension Line Phase I project, the left line extending from Chuanzheng Culture City Station to Majiangdu Station has a total length of 1,398m. The two ends of the tunnel section are made of full-section long-distance strongly weathered granite, and the middle section is full-section soft soil. In order to effectively eliminate the adverse effects of such complex geology on tunnel construction, the dual mode TBM 'CRES 740' has converted from earth pressure mode to TBM mode for efficient rock breaking and excavation in long-distance ultra-hard rock formation. At the soft soil zone, it will 'turn' into earth pressure balance mode for soft soil excavation. The rapid mode conversion allows for mutual complement of advantage, providing strong support for fast, efficient and reliable tunnel construction.