A force transmission assessment method for thrust system in shield machines based on the relative coefficient in compound ground

An evaluation method for force transmission in the thrust system of tunneling machines in compound ground was investigated in this study. First, the mechanical model for a pushing system in heterogeneous ground was constructed. Then, the relative coefficient of eccentricity on a conical surface was determined based on the mechanical model. Subsequently, the uniformity degree of force transmission in the thrust system was measured using the relative thrust coefficients of eccentricity. Eventually, the performance of force transmission under various arrangements with an equal number of jacks was discussed in detail by applying the conical model of eccentricity to the thrust mechanism of a tunneling machine used in engineering projects. The 3D parameter models for the thrust system of an earth pressure balance shield machine (diameter: 6.34 m) were established using SolidWorks. In addition, a propelling system with 22 hydraulic cylinders was simulated via the automatic dynamic analysis of mechanical systems (ADAMS). Results of the numerical analysis agree well with those simulated by ADAMS. The results provide a theoretical basis and support for choosing a non-equidistant driving system in a composite stratum.