The Yangzhou Dilong EPB3700 earth pressure balance shield machine delivered an impressive performance during the construction of the Yinjiafu Power Tunnel Project in Shunyi, Beijing. Operating stably throughout the works with outstanding tunneling efficiency, the machine successfully overcame construction challenges posed by various complex strata and advanced tunnel excavation tasks to high standards, boosting the quality and efficiency of the regional supporting power tunnel project.

The Yinjiafu Power Tunnel Project in Shunyi, Beijing features complicated construction conditions and high technical difficulties. The shield tunneling section extends 1,540 meters in total, with the tunnel crown buried at a depth ranging from 12 meters to 13 meters. The alignment’s minimum turning radius is merely 250 meters, imposing strict requirements on the shield machine’s steering adaptability, tunneling stability and stratum compatibility. Different from conventional municipal tunnel projects, the tunnel route traverses mountainous terrain with highly variable geological conditions, including upper-soft lower-hard strata, intact hard rock strata and pure clay strata. Great disparities exist in mechanical properties and tunneling resistance among these formations, which may easily trigger tunneling stagnation, excessive cutter wear, stratum disturbance and uneven construction progress, posing a rigorous test to the comprehensive performance of the tunneling equipment.

The project fully adopted the self-developed Yangzhou Dilong EPB3700 earth pressure balance shield machine. Optimized specifically for variable mountain strata, the machine perfectly meets the complex construction demands of the project. Boasting powerful stratum adaptability, it dynamically adjusts tunneling parameters according to the characteristics of upper-soft lower-hard ground, intact hard rock and pure clay. It precisely controls tunneling speed, cutterhead torque and chamber pressure balance to effectively eliminate construction risks brought by alternating strata and ensure smooth and orderly excavation. Meanwhile, it is well suited to construction scenarios of small-radius curves and deep-buried tunnels, fully complying with all technical specifications of the project.

Benefiting from superior equipment performance and mature construction adaptability, the EPB3700 earth pressure balance shield machine achieved efficient tunneling across diverse strata and yielded remarkable construction results. When driving through high-strength mountain hard rock with a compressive strength of 90–130 MPa, the machine delivers steady tunneling power, achieving an average advance of 9 to 11 rings per day for stable and efficient hard rock excavation. In soft clay strata with favorable workability, tunneling efficiency rises significantly, reaching a maximum daily advance of 31 rings. This fully demonstrates the core strengths of the machine in accommodating variable advance speeds and multiple working conditions. Throughout construction, the equipment maintained a low failure rate and produced well-formed tunnels, effectively safeguarding the project schedule and construction safety.

The efficient progress of the Yinjiafu Power Tunnel Project in Shunyi, Beijing fully verifies the robust capability of the Yangzhou Dilong EPB3700 earth pressure balance shield machine in tunnel projects involving alternating complex mountain strata and highlights its wide adaptability across hard rock, soft soil and composite ground scenarios. Furthermore, it accumulates valuable practical experience for power tunnel construction under complicated geological conditions in China, facilitates the improvement of regional power infrastructure, and consolidates the engineering foundation for the safe and stable supply of local electricity.