Load Model And Simulation Studies Of Shield Machine Oriented To Rectification Working Conditions

Shield method has become the major tunneling machine for the construction of underground space due to its advantages of environmental friendliness, wide application scope, low construction cost, etc. And it becomes more and more urgent to strengthen the research, development, production and application of shield machine and its technology. The trajectory rectification is an important issue of shield tunneling. During previous construction, due to lack of load model of shield machine, the rectification relies on the manual regulation of the operator, which depends entirely on the experiences with low control precision. If Load the load model of rectification working conditions can be studied and the automatic control technology can be applied to trajectory rectification, the automatic rectification will be helpful not only to improve construction environment and avoid construction danger, but also to reduce the operations by experience and improve control precision.According to this actual engineering problem, the force loads and determination method of earth pressure are analyzed in this paper based of which the orientation rectification and rolling rectification are studied. And the coordinated control of multiple hydraulic cylinders for the orientation rectification is discussed preliminarily.Firstly, the force loads of shield machine are analyzed. The classification of surrounding loads during shield tunneling, the calculation theory of earth pressure around the shield and different calculation formulas are summarized; a new calculation formula is proposed based on the previous formulas and then finite element simulation is carried out to verify the applicability of the proposed calculation formula.Secondly, the rolling rectification is analyzed. And based on the analysis of impact factors of rolling rectification, the calculation method of main torque moments that influenced the rolling rectification of shield machine is studied and the critical condition of rolling rectification appearing is proposed. Then a practical calculation example is used to prove that the orientation deviation is not liable to happen.Thirdly, the orientation rectification is analyzed. The key issue of shield orientation rectification is the determination of trust force of hydraulic cylinders which is divided into two parts:the determination of forward propulsion and the determination of rectification moment.â‘ The calculation method of forward propulsion of hydraulic cylinders is summarized; â‘¡The finite element method is used to simulate rectification process of shield machine, to study the relationship between rectification moment and angle and also to explore the influence laws of different soil parameters and buried depth on rectification moment. And the rectification moment can be determined by different soil parameters and tunneling parameters.Finally, this paper makes an attempt to study the coordinated control problem of multiple hydraulic cylinders and a double closed-loop controller is proposed for the orientation rectification. The outer loop is responsible for treating coupled effects caused by load forces and giving the dynamic desired trajectories of the cylinder; the inner one is responsible for tracking the desired trajectories and giving the practical voltages to control the electrohydraulic cylinder.