Fluid-soil interaction analysis for jet grouting in sands based on numerical simulation

Jet grouting is a geotechnical consolidation technique commonly used to improve soil mechanicals. Despite its successful applications, understanding micro-level interactions between the jet and soil is incomplete. This paper utilizes the Smoothed Particle Hydrodynamics (SPH) and Arbitrary Lagrangian-Eulerian (ALE) methods to simulate fluid-soil interactions in both non-submerged and submerged environments. Analysis covers the flow fields and soil erosion. Findings show erosion velocity remains steady in non-submerged conditions, with the jet compacting and flushing soil. In submerged conditions, the simulated jet flow field under soil constraint is similar to that in the free submerged conditions. However, influenced by soil deformation, damage, and the backflow of the slurry, the jet flow field under soil constraint displays distinct features. For instance, velocity distributions in certain cross-sections cannot be accurately described by normal distribution, and axial velocity distribution curves exhibit different partitions compared to free submerged jet theory. Comparative simulations vary jet pressures, grout water-cement ratios, and soil compactness to analyze the erosion process. It is found that jet pressure significantly affects the depth of the erosion pit. The limit erosion distance in ALE simulations were compared with theoretical values derived from an established theory, and a model experiment was also conducted to analyze the jet-grouted diameter at different left speeds and rotational speeds of rod. The results show that ALE method can offer high accuracy in predicting the jet-grouted diameter and proves to be a feasible approach for fluid-soil interaction simulations in jet grouting.