Three-dimensional large deformation and plastic failure for cohesionless soil turning by an SPH model with a Drucker-Prager closure

Purpose This study investigates the large deformation and plastic failure mechanisms during three-dimensional soil turning to improve understanding of soil-tool interaction. Design/methodology/approach A numerical model based on smoothed particle hydrodynamics (SPH) and elastoplastic soil theory was developed to simulate three-dimensional cohesionless soil turning. Comparative analyses between two- and three-dimensional conditions were conducted to assess the influence of lateral confinement on soil failure behavior. Findings The simulation results reveal three stages of soil tillage: initiation and propagation of plastic failure surfaces, heaving of failed soil mass, and mixing with surrounding soil. Under three-dimensional conditions, lack of lateral confinement induces lateral expansion, generating 2–3 dominant failure surfaces and lower steady-state peak load; confined two-dimensional conditions exhibit 5–6 distinct plastic bands. Sensitivity analysis of internal friction angle and dilation angle shows moderate ranges preserve the three-stage failure evolution without changing the failure mechanism, while larger values significantly enhance plastic deformation extent. Practical implications These findings provide quantitative insights into soil deformation during tillage, supporting more effective tool designs and improved soil-structure management in agricultural engineering. Originality/value This work presents a detailed SPH-based simulation of three-dimensional soil turning, highlights the limitations of two-dimensional analysis and offers a more accurate approach to modeling complex failure phenomena in soil.