STUDY ON ROCK STRESS OF THESP HARD ROCK LABORATORY SWEDEN

?sp? Hard Rock Laboratoty is a planned permanent repository for nuclear waste in Sweden. In situ stress measurement result indicates that both magnitude and orientation of stress vary greatly. It is thought that these variations are related to the development of fractures. Using diserete element method and UDEC code, the autors simulated the stress field in Aspo area. The simulation considered both plane model and vertical model. The results show that both magnitude and orientation of stress change in the vicinity of fractured zones and coincide well with the measured result. Principal stress reorientes near fractured zone and the reoriented angle depends on the angle between fractured zone and the direction of boundary stress. For the vertical model, the result from lower angle model is similar to the measured result. An approach to determining normal stiffness and shear stiffness of fracture zone is also discussed in the paper.