Abstract
Tunneling in highly permeable ground using a slurry shield machine can be challenging because it is difficult to form the so-called filter cake on the tunnel face to transport the support pressure. Consequently, destructive accidents might happen, such as face instability and water inrush. How to form an efficient filter cake in time is crucial during engineering practice, especially in ground with high permeability. Various theoretical and experimental analyses regarding the formation of filter cakes have been conducted. However, due to the complexity of this problem, which has to incorporate the mechanical and hydraulic behaviors of the fluid–solid mixture system, few numerical simulations are found in the literature. In this paper, with the aid of a newly developed numerical tool, a coupled CFD (computational fluid dynamics)–DEM (discrete element method) simulation is established to study the slurry infiltration and filter cake formation during slurry shield tunneling. The slurry infiltration process is simulated by modelling the scheme of the infiltration column test, in which sedimentation behaviors of slurry particles are captured and compared with experimental results. The results show that the sedimentation behaviors of the slurry particles and filter cake formation phenomenon are well captured by simulations and in accordance with the experiments, which indicates the robustness of the coupled CFD–DEM simulation used in present work.
Highlights
Slurry shield machines are widely used in mechanized tunneling projects, especially in undersea and cross-river tunnels [1]
As As for for thethe porosity porosity distribution distribution above above the the sand sand column, column, no no obvious obvious difference difference occurs occurs between between the the initial initial state state porosity and final state since the slurry particles are too small to clog the pores inside the sand column
Final state since the slurry particles are too small to clog the pores inside the sand column
Summary
Slurry shield machines are widely used in mechanized tunneling projects, especially in undersea and cross-river tunnels [1]. Incorporating constitutive relations between the solid pressure and permeability and the solid fraction of the cake, the partial differential slurry flow. Krause [4] proposed an empirical equation for calculating the infiltration length of slurry from various laboratory tests. The equation showed that the infiltration length was related to the applied pressure, slurry viscosity, and particle size of the ground. In order to study the mechanism of slurry infiltration, a suitable numerical approach is. CFD and approach to investigate the slurryapproach, infiltration filter cake formationabehavior slurry shield tunneling. In this CFD–DEM theand solid phase is formation behavior during slurry shield tunneling.
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