Coordinated Control Technology for Small-Radius Curved Tunnelling Using an Open-Type TBM

Full-face tunnel boring machines (TBMs) in deep coal-mine roadways require coordinated geometric and operational control for small-radius turning. Using the EQC5030 open-type TBM and the Xin’an Coal Mine roadway layout as an engineering case, this study develops a theoretical planning framework combining geometric screening, overcutting allowance, differential steering, periodic unloading, and lithology-dependent adjustment. For an effective machine length of 16 m and an articulation angle of 12°, the simplified radius reference is 76.96 m, compared with the project target of 70 m. A common-chord calculation gives a local sagitta difference of 41.93 mm. An 80 mm radial allowance leaves 38.07 mm in this local budget before operational and geological deviations are included. A 1.5 m advance requires an angular increment of 1.23° on the 70 m alignment. Consistent reference coordinates and a proposed unloading schedule are provided, with feedback correction required when the steering increment changes. Calculation checks reproduce the reduced-model results; system-level coupled simulation will be pursued in subsequent research to examine the coordinated control response. The framework links geometric calculations to candidate operating settings and identifies the cutter-envelope, clearance, and equipment-limit checks required for application. It supports preliminary design assessment rather than establishing a revised certified minimum turning radius.