Abstract: Primary technologies such as excavation, propulsion, and direction adjustment of the U-shaped shield pipe erecting machine are examined in a utility tunnel project in Xiong′an. The objective is to explore the key technology of integrated shield excavation-pipe erection construction of prefabricated utility tunnels and improve the mechanized construction level and efficiency of prefabricated utility tunnels. A propulsion force model of the U-shaped shield pipe erecting machine is constructed to analyze the influence of the reserved core soil on improving propulsion resistance. The under-xcavated volume of the core soil corresponding to the sealing compressive force required by different sections of pipe is obtained from an established mathematical model to validate the feasibility of using the propulsion hydraulic cylinder to compress the sealing of the pipe joint in the U-shaped shield pipe erecting machine. Assisted by the insert cutters and propulsion plates for over- and under-excavation, the excavation attitude of the machine is controlled within ±20 mm under the coordinated control of jacking hydraulic cylinders and articulated hydraulic cylinders. Under horizontal and vertical broken-line turning conditions, a wedge-shaped transition bridge with adjustable ring width can realize 7.7° horizontal broken-line turning and 70‰ longitudinal broken-line turning of the U-shaped shield pipe erecting machine. Finally, the cooperative construction technology of the U-shaped shield and pipe erecting machine during excavation, direction adjustment, and pipe installation is explored. The U-shaped shield pipe erecting machine exhibits feasibility in excavation, propulsion, direction adjustment, and pipe installation of the prefabricated utility tunnels.

Key words: utility tunnel, construction equipment, Ushaped shield pipe erecting machine, sealing compressive force, attitude control, broken line turning