Parameter Optimization Of Shield Propulsion System Based On Surrogate Model

Shield machine is a kind of industrial tunneling system that integrating electrical,mechanical,hydraulic and other multi-disciplines.The hydraulic propulsion system is responsible for the jacking task,ensuring the shield machine digs along the predetermined axis and completes the correction and attitude control.During the construction of the shield machine,it is necessary to adjust the tunneling speed and pressure of the shield propulsion system.During this process,the pressure and flow in the hydraulic propulsion system will be disturbed.Excessive disturbance will destroy the pressure balance and cause accidents such as surface bulging and settlement.The shield will also be damaged by the impact of the hydraulic cylinder support.In this paper,CFD numerical simulation technology is used to study the disturbance caused by adjusting the parameters of hydraulic propulsion system during the tunneling process of shield machine.The proxy model and optimization algorithm are used to optimize the system parameters(valves and pipelines),and the hydraulic propulsion mechanism is analyzed.Dynamic characteristics,the dynamic characteristics between the moving platform and the static platform of the propulsion mechanism under different working conditions are obtained.The specific research contents of this paper are as follows:(1)Taking the hydraulic propulsion system of the earth pressure balance shield machine as the research object,study the disturbance caused by the adjustment of the hydraulic propulsion system of the shield.According to the 6.5-meter shield hydraulic propulsion system,establish a three-dimensional model of the system.The grid scheme adopts the hybrid grid and the dynamic grid technology are used to simulate the pressure and flow changes caused by the hydraulic propulsion system.(2)Based on the analysis of the pressure disturbance caused by the adjustment of the hydraulic propulsion system of the shield,the parameters of the hydraulic propulsion system are optimized based on the proxy model method and the optimization algorithm.Considering the structural parameters and oil parameters of the hydraulic propulsion system valves and pipelines,the selected parameters are screened by orthogonal test design method to select the main parameters that have great influence on the pressure disturbance amplitude.The training sample points are selected in the sample space using the optimal Latin super-living method.The support vector regression method,radial basis function method,response surface method and Kriging method are used to construct the proxy model.The multi-determination coefficient and the mean square error are used as the evaluation criteria.The cross-validation results show that the Kriging model has the highest precision.The Kriging proxy model is applied,and the simulated annealing algorithm(ASA)is used to optimize the target of the pressure model.The global optimal solution of the proxy model is solved and verified by CFD.The research results show that the pressure disturbance amplitude after optimization based on the proxy model is significantly reduced,which provides an effective reference for the design of the shield hydraulic propulsion system and the speed and pressure control during the shield tunneling process.(3)According to the four-zone mechanism of the propulsion system,the equivalent model of the 4SPS parallel mechanism is constructed,and the dynamic characteristics are analyzed.According to the control method of the system pressure,the hydraulic cylinder,the support shoe and the ball joint in each zone are equivalent to one SPS branch,the whole propulsion mechanism is equivalent to the 4SPS parallel mechanism.The position analysis,speed analysis and statics of the moving platform are performed.Analysis the force state of the parallel mechanism moving platform and the static platform when the shield machine is tilted up,down,and left and right.