Acta Geodynamica et Geomaterialia

Title: APPLICATION OF DIRECT AND INDIRECT METHODS FOR PREDICTING GEOTECHNICAL DAM FOUNDATION ISSUES ON WEATHERED METAMORPHIC ROCKS UNDER TROPICAL CONDITIONS
Authors: Leao Marcio Fernandes and Marques Eduardo Antonio Gomes
DOI: 10.13168/AGG.2020.0002
Journal: Acta Geodynamica et Geomaterialia, Vol. 17, No. 1 (197), Prague 2020
Full Text: PDF file (3.2 MB)
Keywords: Karst Cavities, Electrical Resistivity, Concrete-Gravity Dam, Weathering Rocks
Abstract: Weathering profiles in tropical regions usually present great heterogeneity and anisotropy of geological materials. High structural complexity and great bedrock irregularity are added when these profiles are composed of metamorphic rocks. Therefore, geological-geotechnical research initiatives in these regions imply indirect methods associated with direct methods. In this context, we studied the San Juan dam foundation in the Dominican Republic, geologically composed of young residual schist soil cover (up to 20 m), in which occurs schist layers of low resistance to SPT (2 SPT blows/30 cm) consistent with a massive and stratified marble rock, which tends to concentrate karst cavities. This geological condition, associated with the vast extent of the dam influence area, motivated the adoption of an indirect method by electrical resistivity intending to identify sites with the possibility of occurrence of cavities filled or not under the reservoir foundation and in the dam axis itself. Subsequently, a more rational initiative of mixed drillings was carried out in sites with such possibility, resulting in discarding these hypotheses and demonstrating that these cavities correspond to graphite schists and non-karst marbles, competent materials as dam foundation.