Research on characteristics of deformation in thrust system for EPB shield machines

The purpose of the research is to investigate into characteristics of deformation in thrust system which reduces the stiffness with the increase of displacement for piston in hydraulic cylinder. Firstly, based on the hyperstatic compatibility, the spatial deforming ellipse for the driving system has been discovered. Then the characteristics for the deforming ellipse of even and non-uniform arrangement systems have been analyzed in detail. Finally, applying deforming ellipse to the thrust systems of a shield machine in engineering applications, the characteristics of the deforming ellipse affected the behavior of the thrust system have been discussed. The result could provide a theoretical foundation and support for the design of thrust systems in shield tunneling machines.