National strategic crude oil storage in the Weeks Island Dome Salt Mine--2. Rock mechanics evaluation

A rock mechanics evaluation to assess the structural stability of the old mine workings of the Weeks Island Dome Salt Mine in conjunction with a proposed new deeper mine level during the use of the facility for the long-term storage of crude oil under the U.S. Strategic Petroleum Reserve Office involved laboratory testing of the strength and deformation characteristics of the rock salt, determination of a minimum web or sill thickness between the old workings (within which crude oil would be stored) and the proposed new mine level development below, and assessment of the effects of crude oil emplacement and withdrawal on the mine stability, as related to both the old workings and the proposed new mine level development. The finite-element results, in which use was made of the strength and deformation properties of the salt, indicated that a minimum sill thickness of 300 ft should be maintained between the old mine workings and the new level development.