Numerical Models of the Deformation Behavior of Rigid Bodies with Decreasing Strength in a Ductile Matrix

Summary Generic, numerical 2D models were used to simulate the linear-elastic deformation of a strong waste canisters in a weak rock salt matrix. During deformation the Young’s modulus of the canister materials steel and copper was lowered and the Poisson’s ratio raised to simulate mechanical weakening of the canister; the rock salt matrix remained mechanically unchanged. Consequently, the canister became with time weaker than the surrounding rock salt matrix. The canisters were either empty or filled with steel in the model. Our results show clearly, that (1) deformation gets more pronounced with increased mechanical weakening of the canisters, (2) a copper canister develops a higher ellipticity than a steel canister and (3) a strong, competent body in a weak, incompetent matrix shows different deformation patterns than a weak, incompetent body in a strong, competent matrix. Around a strong body in a weak matrix concave strain and stress trajectories are observed plus material displacement towards the model margins. Around an incompetent body in a competent matrix material displacement from the model rims towards its center is observed and convex strain and stress trajectories occur. Our simplistic models will help to strengthen our general comprehension of deformation processes in nuclear waste disposal systems.