Layout optimization of non-equidistant arrangement for thrust systems in shield machines

• The design principles mainly depend on force transmission characteristics.
• The system layout should be based on given geological conditions.
• An uneven system transmits force more evenly than a pacing one under special conditions.
• An uneven system excavates with more accuracy than a pacing one under special conditions.
• The resonance in an uneven driving system may be avoided.

This study aims to find a non-equidistant arrangement configuration that allows the even application of forces on rear segments under specific geological conditions. While providing an allowance for stagger-jointed segmental lining, the thrust system in an earth pressure balance shield machine with a diameter of 6.34 m and 24 jacks is optimized in a non-uniform arrangement based on the force transmission and deformation characteristics of a non-equidistant driving system. The contour of the force ellipse eccentricity of the optimized uneven system demonstrates that segments are effectively protected when the forces applied by the jacks are almost equal. The deformation differences prove that the optimized driving system has high control accuracy in tunnel construction. Frequency analysis shows that the optimized driving system can also avoid resonance. The results of this work can provide a theoretical foundation and support for the design of uneven driving systems in shield tunneling machines.