Modelling of the bedrock response to glacial loading at the Olkiluoto site, Finland

The Olkiluoto Island is situated in Baltic Sea, near the southwestern coast of Finland. The most abundant rock type is migmatic mica gneiss, intruded by tonalites, granodiorites and granites. Response of bedrock at Olkiluoto site was modelled with 3DEC program considering four future ice age scenarios. Each scenario produces shear displacements of fractures with different time of occurrence and varying recovery rate. Generally, the larger the maximum ice load, the larger the permanent shear displacements will be. For basic case, the maximum shear displacements were few centimeters at suggested nuclear waste repository level. The sensitivity study performed showed that shear stiffness and joint friction angle of bedrock structures are the most critical parameters for bedrock displacements.