Assessment and structural improvement on the performance of soil chamber system of EPB shield assisted with DEM modeling
This paper assesses the adaptability of the soil chamber system of a earth pressure balanced (EPB) shield machine to be used in sandy pebble stratum by the discrete element method (DEM) modelling. Furthermore, measures for the structural improvement for better fluidity and higher wear resistance are proposed based on the analysis results from DEM accordingly. Firstly, the flow characteristics of particles inside the chamber was obtained through investigation of velocity field, motion trajectory and mass flow rate. Secondly, the abrasion loss on cutterhead and the maximum tunneling distance without changing tools was predicted. Thirdly, through particle-structure interaction (PSI) analysis, the stress and deformation information about cutterhead in a quasi-static state was output. Fourthly, on-site measured data indicate that the power supply device can fulfill the requirement of thrust force and cutterhead torque. Finally, the strength, abrasion loss and internal pressure of screw conveyor were checked. Overall, the selected chamber system shows a satisfactory performance. Furthermore, the proposed improvement measures were verified through DEM simulation, which can provide references for further optimization design of shield chamber.
Keywords: EPB shield machine, Soil chamber system, Performance assessment, Structural improvement, Discrete element method