Recently, as the cutterhead of the "Qijie Hao" shield tunneling machine broke through, the right line of the section from Fo'erya Station to Hechuan Road Station (hereinafter referred to as the Fo-He section) of the second phase of the Qingdao Metro Line 2 project was successfully completed. The project is supervised by the Qingdao Municipal Public Utility Engineering Quality and Safety Supervision Station, constructed by the **Construction Branch of Qingdao Metro Group, undertaken by China Railway Construction Corporation Limited, and executed by China Railway 25th Bureau Group.

The Fo-He section of the second phase of Metro Line 2 completed this time has a total length of 960 meters. The longitudinal profiles of both the left and right lines are of the "straight" slope type, with a maximum longitudinal slope of 29.63‰. During construction, the project had to face a Class I risk source consisting of passing beneath the Houjiazhuang River and passing alongside the piers of the Jinshui Bridge. At the same time, it faced a series of difficulties such as frequent transitions between sand layers and stratum lithology, water and sand inrush, cracks caused by tilting bridge piles, and difficulty in maintaining pressure at the tunnel face. To ensure shield tunneling construction, the **Construction Branch, together with China Railway 25th Bureau Group, formed a shield construction "brain trust" that carried out detailed investigations of the structural form of the Houjiazhuang River, the silt thickness, riverbed waterproofing measures, and surrounding seepage and leakage conditions. They also communicated fully with the design unit, shield machine manufacturer, and well-known domestic experts and planned in advance, ultimately achieving safe tunneling.

"These achievements are attributable to the application of intelligent management methods. By using new-generation information technologies such as BIM, AI, and the Internet of Things, we built an intelligent control center that enables intelligent 'sensing, transmission, cognition, and control,' intelligently acquires on-site data such as video images and quality, safety, and progress data, and constructs an intelligent, efficient, green, and lean 'Internet Plus' integrated visual management platform for the construction site. At the same time, we also optimized the collaborative control application system for the shield intelligent interconnection project, enabling 'all-weather monitoring, whole-process supervision, all-round analysis, and full-business linkage,'" introduced project manager Guo Mingjun. Recently, the project was also commended in a circular by the Qingdao Municipal Public Utility Engineering Quality and Safety Supervision Station for its outstanding performance in summarizing and promoting intelligent management experience across the city.

Thanks to the application of the above intelligent management methods, Liu Shuai, a shield machine operator in the Fo-He section, found his work during tunneling much more manageable. He said that the smart construction site system allows more intuitive monitoring of stratum changes, the effectiveness of muck conditioning in the soil chamber, and tool wear, and transmits shield construction data such as earth pressure, thrust, torque, attitude, and synchronous grouting volume in real time to the construction management platform. Effectively integrated with the equipment PLC system, it can show in real time the changes in muck discharge weight with the advancing stroke, the total muck discharge weight per ring, and changes in the soil discharge coefficient, and reflect in real time whether there is over-excavation or under-excavation and geological changes. Through the shield tail gap real-time monitoring system and the real-time muck weighing system configured for the shield, measurement error can be controlled within ±3 millimeters and measurement accuracy within 1 millimeter.