Investigation on synchronous grouting process during shield tunneling in coarse grained ground using CFD-DEM approach

• Published in: Computers and geotechnics Vol. 170; p. 106308
• Main Authors: Liu, Chao, Zhu, Delin, Cui, Jie, Jing, Lu, Huang, Xin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2024
• Subjects: CFD-DEM; Coarse grained ground; Grout spreading mode; Shield tunneling; Synchronous grouting; CFD-DEM; Synchronous grouting; Coarse grained ground; Grout spreading mode; Shield tunneling
• ISSN: 0266-352X; 1873-7633
• DOI: 10.1016/j.compgeo.2024.106308

Synchronous grouting plays a pivotal role in the shield tunnelling for mitigating the surrounding soil displacement. A Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model is developed to study the soil-grout interaction in this process during shield-driven in coarse grained ground. The Volume-of-Fluid method is employed to simulate the grouting behavior in CFD. A DEM model undergoes calibration of micro-parameters based laboratory tests. The validation of the CFD-DEM model is conducted based on an existing scaled model test. After shield passing, the surrounding soil deforms towards the tunnel, covering the tail-void above the waist of the tunnel. Consequently, grout injected from the upper opening predominantly spread through permeation in a half-spherical mode centered on the grouting opening, spreading to the waist of the tunnel under gravity. Grout from the lower opening initially fills the tail-void, shifting to permeation thereafter. As the grouting-volume-ratio (GVR) is increased, the radial spreading distance from both the upper and lower openings significantly expands. The impact of the grouting pressure is investigated, and two indexes (i.e., grout cover ratio and grout loss ratio) are defined to evaluate grouting variables. Optimal grouting results are observed at a 7:3 ratio between the pressures at the upper and lower openings.