Based On The Hydraulic Constant Pressure Network Shield Soil Pressure Balance Control Study

Shield construction is the most efficacious method to construct tunnel now in the world. Earth pressure balance (EPB) shield is used most extensively in shield construction. Research to improve performances of EPB system has direct engineering significance, because performances of EPB system directly affect the construction quality and efficiency of EPB shield. For it is not economical and safe to research in working field, an electro-hydraulic simulation system of EPB system based on hydraulic power control principle is proposed in this paper. We expect to find out how to improve performances of EPB system through researches on the electro-hydraulic simulation system of EPB system.At present, pump-controlled motor system is widely used in EPB system. It cannot satisfy engineering requirements on some occasions, because this system is always affected by some time-varying or nonlinear factors, such as soil, dead space of variable pump, and so on. That may cause some dangers, such as cut face slide, ground movement reach an unacceptable level, and so on. The system composed of variable-displacement hydraulic motor and constant pressure network has been proved superior to pump-controlled motor system in response speed and efficiency. It is a reasonable deduction that dynamic performance of EPB system may be improved and EPB system may be more efficient if this technology is adopted in EPB system. These help maintain the tunnel face at rest, minimize ground movement and reduce construction costs.An electro-hydraulic simulation system of EPB system based on hydraulic power controlprinciple is proposed after analysis of composition and operating principle of EPB system in this paper. According to the mathematics model of EPB system, the electro-hydraulic physical simulation system was built. By regulating electro-hydraulic control variables and parameters, the system can realize to simulate situations of soil input and output, as well as changes of soil property and forward-velocity of the machine. Experiments prove that the priciple of simulation system is right, simulation is convenient and experimental efficiency is high.The most important purpose of this paper is to study different performances between the electro-hydraulic simulation system of pump-controlled motor EPB system and the electro-hydraulic simulation system of EPB system based on constant pressure network through experiments. After study on performances of the electro-hydraulic simulation system of pump-controlled motor EPB system using PID control algorithm, a reversed variable integral gain PID control algorithm is proposed to solve contradiction between response speed and steady state precision of the electro-hydraulic simulation system of pump-controlled motor EPB system. Then a fuzzy self-turning PID control algorithm including reversed variable integral gain idea is proposed. Experimental results show that the electro-hydraulic simulation system of pump-controlled motor EPB system using these two control algorithms has better performances than that using PID control algorithm. It has some reference to improve performances of pump-controlled motor EPB system.Author primarily used PID control algorithm and fuzzy self-turning PID control algorithm in experiments of the electro-hydraulic simulation system of EPB system based on constant pressure network. Experimental results show that performances of the electro-hydraulic simulation system of EPB system based on constant pressure network are much better than those of the electro-hydraulic simulation system ofpump-controlled motor EPB system when using same control algorithm, even the former use simpler control algorithm. It has some reference to the design of a new type EPB system.Author thinks, only some advantages of the electro-hydraulic simulation system of EPB system based on constant pressure network had been proved in this paper. Author believes that along with more work of the project, some other advantages of the electro-hydraulic simulation system of EPB system based on constant pressure network will be exhibited.