A New, Multi-Scale Perspective on Polymer Support Fluids

Polymer fluids have emerged as promising alternatives to bentonite-based slurries in excavation support applications for piles and diaphragm walls. However, their flow behavior and mechanical interaction with soil grains remain insufficiently understood. This paper presents a multiscale numerical framework based on pore-network modeling (PNM) to investigate non-Newtonian polymer flow in porous media and its implications for excavation support. A customized PNM approach is developed to simulate flow patterns, flow heterogeneity, and grain drag forces in sphere packings representing sandy soils. The results reveal three distinct flow regimes. A non-linear drag-pressure gradient relationship above a critical threshold is predicted, and the implications for safety factors in design are discussed. The framework is extended to a field-scale penetration model using a generalized Darcy’s law, capturing the transition in polymer penetration dynamics over time. The findings provide valuable insights for the design and assessment of polymer fluid-supported excavations.