Application of polymer split grouting technology in earthen dam: Diffusion law and applicability

•A visualized numerical model of polymer directional fracturing grouting considering the time-varying viscosity and swelling characteristics of slurry was established.•The diffusion mechanism of directional fracturing of polymer under the influence of grouting hole type, grouting amount, grouting rate, soil elastic modulus and cohesion was revealed.•A small fracturing pore-forming device was developed, and the polymer directional splitting grouting technology was applied to the practice of slope anti-seepage reinforcement engineering.•High density electrical method and DCP penetration test were used to evaluate the anti-seepage reinforcement effect.