Improving the Quality of Foundation Construction on Permafrost: Comparison of Numerical Simulation Results with Field Test Data of Drilled-And-Grouted Steel Piles in Permafrost Conditions

The results of numerical modeling of a drilled-and-grouted steel pile (outer diameter 219 mm, steel grade 09G2S) performed in the ANSYS Workbench software suite, considering both vertical and combined loading conditions (vertical force, lateral force, and bending moment). The simulation was carried out for permafrost conditions at an experimental test site in Yakutsk, Russia, using a two-layer geological model: seasonally thawed silty sand (0–2 m depth) and perennially frozen clayey soil (2–15 m depth). To enhance the physical realism of the analysis, elastoplastic soil constitutive models were employed-MO Granular for the thawed layer and Cam-Clay for the frozen layer-and the presence of a cement–sand grout (CSG) was explicitly accounted for, both as internal pile filling and as an external 50-mm-thick sheath around the pile. The simulation results were compared with field test data from 18 instrumented piles and with a previously developed numerical model implemented in MIDAS GTS NX. Under a vertical load of 98.1 kN, the computed settlement was 4.67 mm, with a maximum von Mises stress of 22.24 MPa. Under combined loading (vertical force = 118.0 kN, lateral force = 34.0 kN, bending moment = 28.3 kN·m), settlement increased to 16.5 mm, and peak stresses rose to 23.5 MPa, localized at the “pile–CSG–air” interface zone. All stress values remain well below the yield strength of 09G2S steel (345 MPa), confirming the structural adequacy of the pile design. The study demonstrates that the use of physically grounded soil models (MO Granular and Cam-Clay) in ANSYS provides a more accurate representation of the stress–strain behavior compared to the simplified Mohr–Coulomb model used in the earlier MIDAS GTS NX simulation. However, calibration against field data is essential to account for real-world material heterogeneities, construction imperfections, and localized defects. These findings contribute to improving the quality, reliability, and safety of pile foundation design on permafrost, particularly in support of strategic infrastructure projects in the Russian Arctic.