Abstract: The rectangular pipe jacking tunnel under Nanhu avenue in Jiaxing, China, is the world′s first 15m diameter and threelane pipe jacking tunnel. Targeted designs are implemented on the multicutterhead excavation, antifriction slurry grouting, and triple screw conveyor mucking systems to ensure the safe and efficient excavation of superlarge crosssection pipe jacking under shallow soil and small clear distance conditions. Furthermore, statistical analysis is conducted on the main tunneling parameters of the pipe jacking machine and ground settlement monitoring results. Some conclusions are drawn as follows: (1) The friction reduction measures adopted effectively reduce the ground friction resistance of the pipe joint, and the actual total thrust is approximately 40% of the theoretical value. (2) The cutterhead diameter and mounting height considerably affect the torque. The average torque is less than half of the rated torque, so it can be optimized. (3) In the pipe jacking process, the shield shell is subjected to large stratum extrusion pressure, the residual earth pressure in the soil chamber is significantly greater than the lateral earth pressure of the stratum, and they both reduce after shield shutdown. (4) After pipe jacking excavation, the transverse surface settlement groove shows a U shape, and the stratum settlement within 0.5 times the excavation width on both sides of the tunnel is large.

Key words: superlarge rectangular crosssection pipe jacking tunnel, multicutterhead excavation system, antifriction slurry grouting system, triple screw conveyor mucking system, tunneling parameters, jacking force, cutterhead, torque, ground settlement