Recently, the EPB/TBM online dual-mode TBM jointly developed by CRCHI and China Railway 17th Bureau successfully broke through the left line of Dailing Tunnel on the Fuzhou Binhai Express Line. This is the first tunnel breakthrough of the entire Fuzhou Binhai Express Line project, marking a good start for the construction of the Fuzhou Binhai Express Line.

Tunnel breakthrough

The Dailing Tunnel, which broke through this time, has a total length of 1488m. The tunnel section contains both soft soil strata and extremely hard rock strata, with the maximum compressive strength of rock reaching 200MPa. To adapt to the changes in complex geology, the equipment integrates EPB mode and TBM mode, which can meet the requirements of rapid excavation in long-distance hard rock as well as excavation in complex strata such as soft soil, soft rock, and upper-soft-lower-hard conditions. Through simple component adjustments, the two modes can be quickly and flexibly switched, greatly reducing equipment investment costs.

Factory acceptance of the equipment

The EPB/TBM online dual-mode TBM started its launch by passing beneath important structures such as a foreign language school and existing railway lines. After excavating over a hundred meters, it entered full-face hard rock. China Railway 17th Bureau and CRCHI joined forces to safely and quickly complete the conversion from EPB mode to TBM mode. During construction, the equipment achieved a maximum daily advance of 27m and a maximum monthly advance of 389m, setting the highest single-day and single-month TBM excavation records for the Fuzhou Binhai Express Line.

Launch ceremony at the site

With the strong support and assistance of Fuzhou Metro Group Co., Ltd. and China Railway 17th Bureau, CRCHI researchers completed a variety of targeted designs for the dual-mode TBM, including a dual-mode heavy-duty cutterhead, an online dual mucking mode, a high-reliability main machine, a rapid mucking system, and multi-level reinforcement measures. These designs effectively solved a series of construction challenges such as small launch site, crossing fault fracture zones, difficult cutter replacement, long-distance hard rock excavation, and efficient rock breaking, providing strong guarantees for the tunnel breakthrough and the smooth completion of the project.

The tunnel after breakthrough