Following the reception of the first dual-mode TBM on the left line of the Shan-Wu section on May 22, good news came again from Qingdao Metro Line 8 on May 31 — the second dual-mode TBM was successfully received, marking the smooth double-track breakthrough of the TBM tunnel in the Shan-Wu section (from Shandong Road South Station to May Fourth Square Station).

The TBM tunnel in the Shan-Wu section of Line 8 has a burial depth of 24.8 to 35.5 meters and a length of 890 meters. It is mainly located beneath Shandong Road, passes through major roads from Minjiang Road to Jiangxi Road, and connects to the large cross-section of the Shan-Wu section parking line.

The line passes beneath numerous risk sources, including power supply, rainwater and sewage, and gas pipelines as well as underground passages, and the geological conditions are complex.

Adverse factors such as crossing six water-rich fault fracture zones, hard surrounding rock, extremely high uniaxial compressive strength, and frequent cutter changes all became "stumbling blocks" in the construction process, resulting in high safety risks and great difficulty.

In the face of difficulties, Qingdao Metro invited well-known domestic experts for "consultation" and conducted "desktop drills" targeting existing risk points. During construction, a digital platform was used to carry out 24-hour monitoring of on-site safety, quality, progress, and risks, continuously optimizing TBM tunneling parameters and timely controlling surface settlement data, laying a solid foundation for ensuring the smooth breakthrough of the TBM tunnel.

The southern section of Line 8 has a total length of 13.1 kilometers and comprises 8 stations. Civil works are currently being fully advanced, and the Yan-Nan, Nan-Jia, and Shan-Wu sections have already been completed.