| Slurry shield machine as a type of technology-intensive tunneling equipment consists of propulsion system,supporting system,slurry circulation system,air pressure holding system and other subsystems,which also uses the bentonite suspension to support and stabilize the excavating face.Establishing the balance between slurry supporting pressure and expected water-earth pressure is an important criterion to ensure excavating face stability in shield tunneling.Because both the present researches and engineering experience do not ascertain the dynamic relationships between the actual slurry supporting pressure and the shield operation parameters,and the time-varying delays and complex disturbances of actuator systems are also not tackled effectively,so the manual operations of slurry pressure regulation will inevitably suffer from inaccuracy and hysteresis and may result in ground deformation.As a result,it is necessary for the desired water-earth pressure tracking and excavating face stabilization to research on the complex dynamics of slurry supporting system and establish the reliable identifier which connects the slurry pressure and shield operation parametersBased on the major scientific and technological project of Henan province and the in-site data collected from the construction of an intermediate section of Wangjing railway tunnel,this thesis presents a multi-step ahead predictive control system for slurry pressure balance which can online produce the optimal slurry level and air pressure considering the logical control sequence between slurry circulation system and air pressure holding system,namely provide the effective tracking targets for the slurry pressure regulation systems.Thereafter,this thesis not only elaborates the robust control systems for slurry level regulation and air pressure holding,but also proposes the global optimal performance index for the controller tuning.In order to improve the practicability of the proposed control systems in shield tunneling,this thesis also design the online error-driven real-time synthetic control system which can track the slurry level and air pressure precisely.In view of the above description,the adaptive control strategies for the slurry pressure balance in shield tunneling are detailed completely and at the same time,this thesis also describe the design processes of a slurry shield testing stand with the diameter 2.5m,which also provides a proper test platform for the verification of the research results in this thesis and the settling of the practical problems encountered in the slurry shield tunneling.The major researches of this thesis are detailed as follows1.Firstly,present a review on the developing and application of shield slurry machine.Then,introduce the principles of slurry shield tunneling and slurry pressure balance control.At last,analyze the previous researches on the slurry pressure balance control and conclude the corresponding deficiencies.All these preliminaries establish a significant foundation for the researches in this thesis.2.This thesis presents a model predictive control(MPC)system for the slurry pressure balance during construction whose structure consists of a diagonal recurrent neural network(DRNN)that approximates the complex relationship between slurry pressure and tunneling parameters,an optimizer which produces the optimal air pressure and slurry level based on the multi-step ahead predictions,and an evolved particle swarm optimization(EPSO)algorithm.The EPSO equipped with periodic supervisor and mutation operator can update the structure and weights of DRNN concurrently to better cater to the changeable stratum.The optimizer can excellently compensate the time delays in slurry pressure regulation by incorporating the logical control sequence of actuator systems into the EPSO procedure,and also produce the optimal slurry level and air pressure online.The simulation results demonstrated that the presented approach can accurately track the desired water-earth pressure and significantly enhance the robustness of slurry supporting system in tunneling,and the novel EPSO also performed higher convergence speed and precision than the standard particle swarm optimization algorithm(PSO),genetic algorithm(GA)and the dynamical back-propagation algorithm.3.This thesis respectively designs the modified Smith predictor based dynamical sliding mode controller(MSP-DSMC)and disturbance observer based dynamical sliding mode controller(DO-DSMC)for the slurry level regulation and air pressure holding.Not only can the MSP significantly improve the tracking performance of the major controller DSMC,but the MSP-DSMC system can also achieve the decoupling control between the set-point response and disturbance rejection at the premise of effectively compensating the large time-varying delays and as a result,the major controller DSMC and the disturbance rejecter can be designed independently.The DO-DSMC system can tracking the desired air pressure precisely and robustly through automatically estimating the random disturbances and establishing the corresponding sliding surface.Additionally,the stability of the controllers is proved based on the Lyapunov theory4.In order to effectively balance the set-point response,disturbance rejection and control law smoothing of the MSP-DSMC and DO-DSMC systems,this thesis develops the global optimal tuning indies which can also guarantee the robust stability of the controllers against the parameter variations,modeling errors,complex disturbances and time-varying delays.Through incorporating the domain knowledge into the genetic parameters and ameliorating the genetic operators and recombination parameters,this thesis also designs the objective-oriented genetic algorithm(OGA)based on the periodic supervisor and whose superior global searching abilities and convergence properties are also confirmed while tuning the controllers.The simulation results demonstrate that the tuned MSP-DSMC and DO-DSMC systems can track the desired values accurately and robustly without any overshoot which are applicable for the slurry pressure regulation.Then,this thesis develops the online error-driven real-time synthetic control system for the slurry level regulation and air pressure holding.The simulation results also confirmed that the synthetic control system tuned by the online OGA can achieve the real-time precise tracking of the controlled variables,namely the practicability of the proposed control systems in slurry shield tunneling is improved.5.After the theoretical researches for the adaptive slurry pressure balance control are carried out,this thesis designs the slurry shield testing stand with the diameter 2.5m which possesses the functions of imitating shield propulsion load,slurry pressure balance control,slurry circulation and air pressure holding.Not only are the testing theories,design principles,parameters calculation and layout of the testing platform detailed,but the numerical simulations of the two-phase slurry flow in the slurry chamber are executed6.The core findings of this thesis are concluded and the further researches could be implemented based on the findings are also specified for the convenient works of the relevant researches. |
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