Los materiales yesíferos del Terciario de Oviedo y su problemática geotécnica

Abstract

The subsoil of Oviedo consists of sediments of Cretaceous and Tertiary age, with an unconformity between them. The Tertiary series presents typical deposits of lacustrine origin which in several areas of the city consists of evaporites (gypsum). This rock causes geotechnical problems for foundations, since i) its solubility is very high forming cavities and ii) it attacks chemically the structural concrete. In Oviedo several zones with high concentration of gypsum can be differentiated. Its presence is more prominent at Ventanielles-La Tenderina area, where a massive gypsum level up to 18 m thick appears. This level is karstified creating a dense net of superposed caves, which has provoked locally ground collapses and subsidence. A clear example is the structural ruin of several buildings in 1998 in the Ventanielles neighbourhood. Ground settlements whose origin relates to the construction of an undergroung parking lot in the proximities of the affected zone provoked a notable alteration in the conditions of water balance into the subsoil when Tertiary gypsum was cut during the excavation.