Degradation of marls; two case studies from the Iberian Peninsula
Published:January 01, 2010
E. E. Alonso, J. A. Pineda, R. Cardoso, 2010. "Degradation of marls; two case studies from the Iberian Peninsula", Weathering as a Predisposing Factor to Slope Movements, D. Calcaterra, M. Parise
Download citation file:
The strength degradation of two marl formations (Pamplona marls in Spain and Abadia marls in Portugal) is analysed in the paper. In the case of Pamplona marls, a number of large-scale direct shear tests on natural and saturated specimens of the undisturbed material were performed. Tests on marl–concrete interfaces were performed and are also presented. Both cases analysed show that the saturation of the marl leads to a strong reduction of friction and effective cohesion. Negative effects of suction changes on the mechanical behaviour of the marls were investigated in more detail in suction controlled tests on Abadia marls, a more plastic material. A numerical simulation of wetting effects on a marl fragment of finite size helps to identify the nature of degradation mechanisms, which are associated with the development of tensile surfaces inside the marl matrix. They, in turn, are due to the expansive behaviour of the clay fraction of the marl relative to suction changes.
Figures & Tables
Weathering as a Predisposing Factor to Slope Movements
This volume is intended to provide an up-to-date overview of the approaches, methodologies and techniques devoted to better understanding of the weathering conditions of rock masses on slopes. According to the local conditions, a variety of slope movements may take place and involve weathered rock masses. Shallow and rapid soil slips evolving to debris flows are probably the most common type of slope movement. At the same time, deep-seated, intermittent landslides can also affect large volumes of weathered rocks and soils. Despite the high frequency of landslides in weathered materials, and the damage and casualties they repeatedly cause, little is known about the relationship between weathering and slope movements. This book presents worldwide case studies, where a variety of geological and geomorphological settings are discussed. The content is divided into three sections: the first is devoted to broad aspects of the weathering/landslide processes; the second and third sections include papers dealing with igneous/metamorphic and sedimentary weathered rocks, respectively.