Research On The Coordination Of Gripper And Thrust System For Single Gripping TBM

Tunnel Boring Machine(referred to as TBM) is a large tunnel construction equipment in rock layers, a combination of excavation, support, disposal of spoil, lining of tunnel and measurement. It is mainly composed of cutter system, gripper and thrust system, rear support system, backup system and auxiliary equipment etc. The gripper and thrust mechanism is one of the key mechanisms for TBM tunneling, which provides adequate support for the whole TBM and propels the cutter system. But the gripping force is rectified manually and the ground pressure is constant in practice generally. Meanwhile the coupling characteristic between gripper and thrust system and the influence of rock characteristic on ground pressure are neglected. As a result, the surrounding soft rock can be destroyed or the gripper can be slipping down. Then the construction process will be extended and waste more manpower and material. Therefore it is necessary to develop the research on coordinated control of gripper and thrust system combined with surrounding rock characteristic in case of these accident.A gripper and thrust coordinated hydraulic control system was designed, and the description and demand of coordination of gripper and thrust system were proposed. The theoretical formula for calculating ground pressure was presented after the mechanical analysis of gripper system, thrust system and external applied load, and then a dynamic simulation was used to demonstrate the validity of it. The minimum value and the minimum fluctuation of ground pressure for surrounding rock are two primary goals of the coordination, therefore the control strategy of gripper cylinder pressure following the thrust cylinder pressure and displacement and the geologic adaptive control strategy of ground pressure base on PNN rock recognition were proposed respectively concerning the two goals. Finally the strategies were proved by simulation computation. The main research contents of this paper are as follows:In the first chapter, the classification and the domestic and overseas development process of TBM were introduced, and the TBM was single gripping TBM in particular. The present study of mechanical analysis of important mechanisms for tunneling equipment, gripper system and coordination of machines were described, and the shortcomings of previous studies of this research were analyzed. Finally the main contents and significance of this research subject were pointed out.In the second chapter, the working principle for TBM gripper, torque and thrust system was described. The integral spatial stress of gripper was expressed by thrust cylinder pressure, displacement, cutter torque and friction coefficient between gripper and surrounding rock after the mechanical analysis of gripper system, thrust system and external applied load. Then the theoretical formula for calculating ground pressure was presented. Finally the stress between gripper shoe and surrounding rock was preliminarily solved by Ansys, the results showed that the stress of surrounding rock of rotation side was greater than it when advancing straight, and the stress of reverse rotation side was minimum, which can provide judgment when adjusting the gripping force for rotation.In the third chapter, the description and control objective of coordination for gripper and thrust system were proposed, and the gripper and thrust coordinated control hydraulic system was designed according to it. Then the control strategy of gripper cylinder pressure controlled by the thrust cylinder pressure and displacement and the geologic adaptive control strategy of ground pressure base on PNN rock recognition were proposed on the basis of the minimum value and the minimum fluctuation of ground pressure for surrounding rock that are two primary goals of the coordination. Finally the mathematical model of the new hydraulic system was established.In the fourth chapter, the dynamic simulated model of gripper and thrust mechanism was established and solved. Compared with the theory result, the maximum relative error of ground pressure was as small as 1.9%, so the theoretical formula of ground pressure can be regarded as valid. Combined with theoretical formulas and practical tunneling parameters, the simulations were performed on the new hydraulic system based on the proposed control strategies. The results showed that the gripper cylinder pressure can be controlled by the thrust cylinder pressure and displacement, and the maximum relative error was 1.18%, meanwhile the ground pressure was minima. The PNN rock recognition can be used to identify the rock type, the output ground pressure coincides with the safety one with 0.7% maximum relative error, so the fluctuation of ground pressure was minima under conditions that meeting the support demand.In the fifth chapter, the scale TBM test rig of gripper, torque and thrust system was designed. The key mechanisms of TBM prototype parts and fictitious load parts were designed and checked. The hardware and software of the electric control system were designed according to its functions, mainly including the control design on PLC for gripper and thrust system and the man-machine interface development for the test rig.In the sixth chapter, the full text of the work was summarized, and the following research work was prospected.