Results of an international parallel calculations exercise comparing creep responses predicted with three computer codes for two excavations in rock salt

Creep responses computed with the ANSALT finite element code, which was developed by the Federal Institute for Geosciences and Natural Resources in the Federal Republic of Germany (FRG), are compared to responses computed in the United States with the SANCHO and SPECTROM codes for two well defined boundary value problems. One boundary value problem is an idealization of an underground room configuration proposed as a repository for low level nuclear waste. The other is an idealization of a room configuration designed for testing the effect of heat on the structural response of rock salt. Both room configurations represent actual excavations in bedded salt at the Waste Isolation Pilot Plant facility near Carlsbad, New Mexico. The SANCHO and SPECTROM solutions to the boundary value problems have already been compared and analyzed extensively in an earlier parallel calculations exercise. The study presented here is an extension of the earlier exercise and was performed as part of a bilateral agreement between the US and the FRG to exchange technology related to the development of nuclear waste repositories in rock salt. Parameters on which the comparisons are based include both displacements and stresses. A rigorous set of procedures designed to eliminate input errors was followed. The comparisons indicate only minor differences between the ANSALT, SANCHO, and SPECTROM solutions, and in most cases reasons for these differences are clearly identified. 14 refs., 62 figs., 2 tabs