A novel self-adaptive thrust system of shield machine under complex geological working condition

摘要

Thrust system is an important part of the shield machine, which consists of tens of hydraulic cylinders that are grouped for better control. The thrust hydraulic system may perform poorly when it works under unexpected geological working conditions as the control group cannot be adjusted. To improve the thrust performance, a new concept of group-adjustable thrust hydraulic system is proposed. Eight different types of equivalent models for grouped thrust system are presented in terms of parallel mechanism theory. The kinematics and statics are then developed to model the performance of the thrust system further. The uniformity index is introduced to assess the performance of thrusting and then calculated for each grouping modes. The numerical simulations clearly illustrate that the properties of each grouping mode. The uniformity analysis demonstrates that the performance of a certain group mode is determined by its group angle. To help the thrust system adapt to the real-time working condition, the optimization of group angle is established according to the principle of the uniformity minimization. At last, a force accumulation index is proposed to demonstrate the effectiveness of group-adjustable thrust system against the group-fixed one through a case study.