Recently, the earth pressure balance shield machine jointly built by CRCC Heavy Industry and China Railway 15th Bureau for Suzhou Metro Line 6 accurately entered the receiving steel sleeve in the right-line section, marking the completion of the main works of the three stations and three sections of Section VI-TS-05 (Sujin Station–Pinghe Road Station–Suzhoudong Road Station–Zhuozhengyuan Station sections), laying the foundation for the full-line breakthrough.

Shield machine breaking through

Suzhou Rail Transit Line 6 starts from Suzhou New District Railway Station in the west and ends at Xinqing Road Station in Suzhou Industrial Park in the east, with a total length of 36.12 km. The Su-Zhuo shield section is 1,346.9 m long on a single line; during shield construction it must pass through 28 major risk sources including the Suzhou ancient city area, the Shanghai–Nanjing intercity railway, the Beijing–Shanghai conventional railway, and the outer city moat, with high settlement control standards along the entire line. The Ping-Su section is 1,586 m long on a single line, and three reinforced concrete piles are located at the bottom of Pinghe Road Station, each with 22 main rebars of 32 mm diameter threaded steel, placing higher demands on the configuration and adaptability of the shield machine.

Construction site of Suzhou Metro Line 6

Completed tunnel of Suzhou Metro Line 6

The shield machine passing beneath major risk sources and cutting through large-diameter reinforced concrete piles intruding into the tunnel posed a huge test for construction organization and equipment performance. Under the guidance of the owner and industry experts, CRCC Heavy Industry, together with China Railway 15th Bureau, carried out a series of targeted designs for the shield machine, greatly improving its geological adaptability by equipping it with a reinforced soft-ground cutterhead, a high-precision earth pressure balance control system, a slow-speed advancement system, and a multi-level grouting system.

Shield machine accepted and rolled off the production line at CRCC Heavy Industry

During the tunneling through major risk sources, the shield machine kept settlement within 3 mm, achieving the goal of safe underpassing and setting a new domestic record for shield tunneling through large-diameter reinforced concrete piles.