ABSTRACT
To rate rock salt barrier integrity, two local criteria are typically used – the dilatancy and the fluid pressure criterion. However, these local criteria are not suitable to assess the rock salt barrier as a whole. So, even if both criteria are locally exceeded, a tight rock salt barrier may be preserved if an intact rock salt envelope remains that encloses the mine openings. Thus, a non-local criterion of effective barrier thickness is proposed as a criterion for containment capability. The effective thickness of the intact rock salt barrier evolves as a function of time, taking into account present and future uncertainties. The influence of different technical concepts on barrier integrity can be assessed. The effective thickness of the intact rock salt barrier is defined as the shortest distance that a fluid must theoretically pass to intrude from the surrounding, potentially water-bearing rock into the mine openings and comprises different sections that may either be interconnected or may be intersected by one or more possible flow paths. The advantage of the use of this non-local criterion of effective thickness is its capability to describe rock salt barrier performance by a single comprehensible quantity regarding geology and the mine openings that implicitly covers the dilatancy and fluid pressure criteria.
