Abstract :
The semihydrostatic emplacement of waste packages in unlined vertical boreholes in salt domes involves the uncontrolled deposition of the packages in the borehole and their complete enclosure in crushed salt. In order to calculate the pressure distribution in the backfilled borehole section, the borehole filling composed of packages and crushed salt is treated by approximation as a homogeneous medium in the theoretical model. The eigenvalues of the pressure tensor depend on the radial distance r from the borehole centre and on the depth z in the borehole and are thus directionally dependent. Emplacement-typical crushed-salt parameters such as lateral pressure coefficient and friction coefficients were experimentally determined. The calculations show that, according to the semihydrostatic model, the maximum pressure in the borehole does not exceed 107 kPa for a 4001 waste package, that this maximum pressure is already reached at a depth of 9.26 m on the borehole wall and that there is an optimum borehole radius for which stressing of the emplaced packages is minimized.
