This study develops and validates a non-conforming contact algorithm for 2D rigid-body/soil interaction within the Material Point Method (MPM). The formulation couples a dynamic signed-distance field (SDF) with a smooth, non-linear penalty law. Unlike standard nodal-velocity schemes, which often suffer from mesh dependency and artificial noise, this approach treats the rigid body as a non-conforming geometrical 1D mesh. This facilitates the application of traction directly at the soil–structure interface and accommodates large continuous rotations without mesh-conformity constraints. The algorithm underwent rigorous hierarchical validation. Initial verification against analytical solutions and Finite Difference Method (FDM) baselines—using Single-Degree-of-Freedom oscillators and 1D oedometer compression—confirmed the correctness and convergence properties of the implementation. Dynamic capabilities were demonstrated through a plane-strain free-fall wall impact, accurately capturing the kinematic and kinetic behavior of the penetration process. The formulation was validated against experimental centrifuge data for bearing capacity and field data from 2D shear-vane tests. Using independently measured elastic and strength parameters, the proposed framework successfully reproduced the experimental system behavior, confirming its ability to capture the mechanics of soil-rigid body interactions in complex geometries.