Compliance of hydraulic system and its applications in thrust system design of shield tunneling machine

As the most significant performance, compliance of hydraulic system is defined as the capacity to accommodate the sudden change of the external load. Due to the different requirements of the compliant tasks, the existing method for mechanical systems cannot be used in the analysis and design of the hydraulic system. In this paper, the definition and expression of compliance of hydraulic system are proposed to evaluate the compliance of the hydraulic system operating under sudden change load. Because the unexpected geological conditions during excavation may exert sudden change load to the shield tunneling machine, the compliance theory has found a right application in the thrust hydraulic system. By analyzing the basic operating principle and the commonly used architectures of the thrust hydraulic system, a compliance based thrust hydraulic system design method is presented. Moreover, a tunneling case is investigated in the paper as an example to expound the validation of design procedure. In conclusion, the compliance of the hydraulic system can be served as an evaluation of the capability in conforming to the load impact, giving supports for the design of the thrust hydraulic system of shield tunneling machines.