Development and evaluation of a process-oriented 3D finite element model for earth pressure balance shield tunneling

Abstract

Thrust system performs the task of driving the shield machine forward and adjusting its posture, ensuring that the shield advances along a designed tunnel alignment. However, there is still no unanimously agreed approach for incorporating the thrust system in shield tunneling simulation. For this purpose, an attempt is made to embed the parallel mechanism properties of thrust system in simulation, i.e., modeling the thrust system as a 4-spherical-prismatic-spherical (4-SPS) branched chain. Meanwhile, a mesh-to-mesh solution mapping technique is introduced to ensure mesh compatibility across the cutterhead-soil interface without losing the stress history information generated during soil excavation. Thereby, a process-oriented 3D finite element model is developed for earth pressure balance (EPB) shield tunneling. The proposed model is quantitatively evaluated by reproducing a comprehensive field dataset collected from Changsha Metro Line 6 project. It is demonstrated that the proposed model can accurately reproduce the measured data for total thrust, grouped cylinder pressure, and total torque with mean relative errors of 5.8 %, 9.6 %, and 7.8 %, respectively. Moreover, the model can well reproduce the highly varied spatial distribution of the grouped cylinder pressure, highlighting its potential in capturing the mechanics for the posture variation of EPB shield.