Abstract: The early-stage construction of U-shaped shield cushions faces many challenges, such as low mechanization, poor construction quality, and inefficient processes. To address these issues, a novel type of cushion paving system was designed for a U-shaped shield pipe machine applied in the EA4 utility tunnel project in Qidong area of the Xiong′an new district. This system was integrated directly with the U-shaped shield machine. By incorporating a guidance system, the system enables automated cushion blanking and scraping control. The authors introduce the structural characteristics and working principles of the cushion paving system, detailing the arrangement of the scraping device in the shield and the construction methods that allow the system to adapt to various utility tunnel cross-sections. Field application results show that compared to the previous cushion construction methods used with the U-shaped shield machine in Haikou, China, this new system boosts construction efficiency by 67% and achieves paving accuracy within ±4 mm. This significantly improves the mechanization and automation of cushion paving in utility tunnels using the Ushaped shield machine.

Key words: cushion paving, U-shaped shield pipe erecting machine, utility tunnel, scraping control