Parameters optimization and engineering practice of pipe curtain support in subway crossing project

This study used FLAC3D to simulate the pipe curtain support system based on an existing shield tunnel crossing project in Beijing. Taking the settlement control value of 3 mm for the existing tunnel structure as the criterion, this study optimized the diameter, circumferential spacing, and circumferential arrangement angle of the steel pipes, and obtained the reasonable ranges of these parameters as 255 mm–300 mm, 350 mm–374 mm and 168°–180°, respectively. Subsequent statistical analysis of the three key parameters revealed that the steel pipe diameter exerts the least significant impact among them. Based on this conclusion, only the circumferential spacing and circumferential arrangement angle of the steel pipe underwent comprehensive optimization, and obtained the relationship of the two parameters when met the settlement control value of the tunnel structure. The optimization results mentioned above have been effectively integrated into practical engineering applications. This enables the alignment of computational results with on-site monitoring data, thereby offering valuable references for future projects of a similar nature.