Improving geological models using a combined ordinary-indicator kriging approach

The generation of geological models always goes along with the geotechnical engineers' wish to keep the models as accurate as possible. Consequently, a lot of research has been carried out in the last years to decrease geological model uncertainty. The focus was mainly put on the statistics of the mechanical parameters of soil and rock masses that go directly into the safety calculations. Besides the statistical features of the mechanical parameters, care must also be given to the statistics associated with the geometrical parameters of the geological layers. One way to statistically model the underground geometry is through the use of geostatistical interpolation techniques generally known as kriging. However, the most commonly used ordinary kriging techniques produce strongly smoothed model results that lead to an inaccurate regionalization of geological layers. Since geotechnical models are usually on a large scale, such inaccuracies cannot be tolerated. This paper shows how smoothing effects around zero value zones can be reduced significantly by the use of a combined ordinary-indicator kriging approach. (C) 2002 Elsevier Science B.V All rights reserved.