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.