Spatial motion patterns and force transmission characteristics of muck particles in EPB shield tunneling: An FDM-DEM coupling analysis

Abstract

Earth pressure balance (EPB) shield tunneling in sandy cobble strata often encounters challenges such as muck stagnation, severe tool wear, difficulties in chamber pressure control, and low excavation efficiency. To address these issues, this study proposes a novel gradient stress construction strategy based on rigid wall boundaries by integrating the finite difference method (FDM) and the discrete element method (DEM), and establishes a refined FDM-DEM coupled shield tunneling model. Using this model, the pressure distribution and load transfer mechanisms at the excavation face and within the chamber, as well as the motion trajectories, velocities, and spatial distribution of muck particles, are analyzed in detail. The results indicate that: (1) The pressure at the cutterhead spokes is lower than that at the cutterhead openings; the muck pressure within the chamber exhibits significant radial gradient variations, with distinct differences between the left and right sides. (2) The average pressure in the upper regions of both the left and right sides of the chamber is nearly equal, with a stable pressure transmission coefficient of approximately 0.8. An under-pressure advancement strategy is recommended to avoid ground heave. (3) The muck particles follow spiral trajectories, forming dual-vortex stagnation zones in the central region of the cutterhead (0-0.2D, where D denotes the cutterhead diameter) and the support column region of the chamber (0-0.25D). The installation of radial mixing rods on the cutterhead shaft is suggested to improve muck flowability. This study provides new insights for optimizing cutterhead and chamber design, offering significant implications for enhancing the efficiency of shield tunneling construction.

Keywords

EPB shield / Sandy cobble strata / Spatial motion patterns / Force transmission characteristics

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

CRediT authorship contribution statement

Yuxiang Yao: Visualization, Validation, Writing - original draft, Data curation. Yong Fang: Project administration, Writing - review & editing, Funding acquisition, Resources. Chuan He: Resources, Conceptualization, Methodology, Supervision, Funding acquisition. Gongyun Xu: Investigation, Formal analysis, Software. Zhigang Yao: Investigation, Formal analysis. Xiongyu Hu: Resources, Investigation, Formal analysis.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This study was supported by the National Science Fund for Distinguished Young Scholars of China (Grant No. 52425807), the Science Foundation of Sichuan Province, China (Grant No. 2024NSFTD0013), the Sichuan “Top Youth” Special Program for Outstanding Young Science and Technology Talent (DQ202403), the National Natural Science Foundation of China (Grant No. 52478418), and the National Natural Science Foundation of China Youth Fund (Grant No. 52408441).

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