Research On Earth Pressure Balance Control Of Shield Seal Chamber Based On Predictive Function Control

In recent years,the rapid development of cities has made the available space on the ground less and less,so the development and construction of underground space has become the main trend of urban development in the future.The shield construction method has become the main construction method for the underground,seabed and mountain tunnel construction.The main equipment for construction is the shield machine,of which the earth pressure balance shield machine has the widest application range.The earth pressure balance shield machine,as the name suggests,is constructed by the earth pressure in the seal chamber and the pressure of the work surface in the shield construction process.If the earth pressure of the seal chamber cannot be maintained,the ground will be catastrophic accidents such as subsidence and bulging occur.Therefore,in order to avoid accidents,it is practical to use reasonable and effective methods to control the stability of the earth pressure in the sealed compartment.For many of the current research results,the earth pressure balance of the seal chamber is controlled by a single variable,and most of the control is to control the amount of soil discharge by controlling the speed of the screw conveyor,and the influence of the time lag on the earth pressure of the seal chamber is not considered.The theory of predictive function control algorithm is used to study the earth pressure balance control of the sealed chamber.Based on the mechanism analysis of the earth pressure balance control of the seal chamber and the theoretical study of the relationship between the earth pressure of the seal chamber and various parameters,this paper proposes a control method for the earth pressure balance of the shield seal chamberbased on the predictive function control.By combining the predictive function control algorithm with the shield machine’s earth pressure balance control principle,the propulsion speed and the screw conveyor speed are taken as the input,and the seal chamber earth pressure is taken as the output,that is,the system is regarded as a dual input single output system.Based on the mechanism model,the time domain function is transformed into the frequency domain function.The soil pressure prediction model of the shield chamber of the shield machine is established.The predictive function control algorithm is used to design the controller of the earth pressure balance prediction function of the seal chamber.According to the prediction function algorithm and referring to the Smith predictive control idea,the optimal control law of the propulsion speed and the screw conveyor speed is derived.Through simulation verification,the predictive function controller can effectively and quickly track the set value of the upper seal chamber earth pressure,and effectively overcome the impact of time lag on the earth pressure balance of the seal chamber.It has small overshoot,high control precision,good effect and high security.