Mechanical behaviour of Miocene hard soils and soft rocks

摘要

In this paper, a practical methodology used to provide the geological and geotechnical data needed for the nathematical modellign of seismic behaviour of the miocene formations of Lisbon is presented. The miocene series is composed by overconsolidated hard soils and soft rocks and is haracterised by large and frequently abroup vbertical changes in lithological facies. The series is divided into a set of lithostratigraphic units, which are also used in the geotechnical practice. However, lithology variations within each unit are generally of the same order of magnitude of the entire series, makign the geotechnical characterisation and engineering geological mapping rather difficult. In the applied methodology, a large number of lithologies were organised in predfined engineerign geological types, characterised by ranges of properties. The relative space distribution of the types is assessed by analysis of available site investigation data. The ranges of properties of the types and their relative frequency provide the basis for the production of a more accurate input data for the mathematical modelling of seismic behaviour.